• The Anthem of the Heart happens because Jun blames herself for her parents' divorce, which came about because she blabbed to her mom about seeing her dad commit adultery at a love hotel.
• Sayuri "Eve" Ibe of Asteroid in Love is unable to keep secrets well, and this weakness is what leads her to openly reveal her intentions for the Earth Sciences club.
• In Getter Robo Go 1991 episode 11, Gou's insistence on wanting to see Getter Robo's overhaul in progress despite being blocked by some of NISER's staff is what clues in the villains that Getter Robo is currently unavailable, leading to an all out attack on NISER HQ. For his part, Gou completely understands what has happened when he discovers the spybot that relayed this information, and boards the improvised combat machine Guard Robo with intent of stopping the enemy at any cost. He even leaves behind a message with teammate Yuji, asking him to inform Professor Tachibana that "this is due to my carelessness and negligence."
• In Naruto, a flashback to the night of the eponymous character's birth shows Kakashi talking to Rin's grave, wherein he talks about said information. Unbeknownst to him, Obito, who Kakashi believes to be dead, is eavesdropping, and learns the secret — after which he tries to kill Naruto, then unleashes the Kyubi.
• Toriko: In the Century Soup Arc, the heroes journey to Ice Hell on a mission sponsored by wealthy geezer Colonel Mokkoi, who even supplies the party with thermal suits to help resist the cold. Later on, Teppei reveals that the suits are wired with listening devices, and warns them not to say certain things aloud, such as the naturally-occurring Century Soup stock having run out, as Mokkoi will abandon everyone if he learns there's nothing to gain. Then Teppei blurts it out himself, and Mokkoi does just that.

• The plot of Black Bishop is kicked off when the titular spy gets drunk one night and spills secrets of The Board to her random hook-up... who turns out to be a journalist. Said journalist writes about The Board in her paper and accidentally outs several of its operatives, resulting in their deaths. Desperate to fix the mess she created, Black Bishop tries to track down the other operatives to stop them from being killed.
• Little Witches: Magic in Concord: Meg, when introducing herself and Jo to the newly moved in Witch Hunter Mr. Laurence, says they don't use magic to grow their apples. Jo immediately follows by saying they only used magic to keep the garden from freezing over in winter and it's since been removed. However, Mr. Laurence isn't one to investigate witches that cause no trouble and isn't after them, but a more pressing situation of a spell causing things to disappear around Concord.
• Wonder Woman Vol 1: Long before she crafted herself a costume and became Cheetah out of envy for the attention Wonder Woman gets, Priscilla Rich was making a bit of extra money on the side by selling military secrets to Imperial Japan. She gained knowledge of said secrets by being friends with/blackmailing/terrorizing the wives of military officers who shared more than they should have with their spouses. She later terrified a mind reader into working for her, meaning that military wives didn't even need to say anything for Pris to steal information from them.

Crossovers

• In As N Approaches Infinity, nobody informed Ichigo that he should keep the reason why a megalomanical Shinigami would want to take over Karakura Town to himself. He passed that knowledge on to his sister Karin, who later tells Kyubey.
• The Elements of Harmony and the Savior of Worlds: In The Conversion Bureau: United We Stand, Flash Sentry accidentally reveals that the vials he was carrying when he was captured were samples of the conversion potion, allowing work to start on an antidote.
• Lelouch of the Wings of Rebellion: Cecile laments Lloyd's tendency towards this when he casually reveals that Prince Schneizel and Princess Euphemia will be visiting Kamine Island, complaining that he really shouldn't share such sensitive information freely.
• One to Find All features several such moments of carelessness:
  • Izuku accidentally reveals that Salem is unkillable to Glynda, having mistakenly assumed that as a moment of Oz's inner circle, she was already aware of that information.
  • Ruby overhears Izuku explaining the whole situation with Salem and the reincarnated heroes to Katsuki, and relays this information to Yang. When they then mention Salem's name, Taiyang's reaction confirms her existence to the girls.
  • While speaking with Kali, Yang nearly reveals that they know her daughter Blake, causing Katsuki to snap at Yang to keep her mouth shut.
• Owl House Prime: Skywarp accidentally reveals to the kids just where the Decepticons are keeping Fowler while planning to take them to be interrogated as well. Cliffjumper remarks that Skywarp was never particularly good at keeping secrets.
• RWBY Zero: In a moment of anger, Yang reveals that Raven is participating in the Holy Grail War... to Gilgamesh. Up until her slip, Gilgamesh had fully believed that he'd already killed Raven for stealing his treasures, and promptly decides to hunt her down, much to Yang's horror.
• Silent Ponyville Chronicles: In Silent Ponyville: Blood Chronicles, Demitri realizes that he's being unusual more open and less careful with his words than he usually is, and begins to suspect it's a side effect of being stuck in a Psychological Torment Zone.

Amphibia

• Confessions shows that Marcy's Motor Mouth tendencies frequently betray her, causing secrets to slip out while she's excitedly rambling on and on. At one point, she nearly tells Sasha about the rebellions before catching herself, but not quickly enough that Sasha fails to notice that she's hiding something.
• In You’re About Seven Years Too Early, Oum overhears the Waybrights complaining about Sasha shortly after the girls vanish, calling their daughter a "parasite" that they should have aborted. Oum swiftly informs the police, leading to Carl and Karen's arrest.

Avatar: The Last Airbender

• Absolute Trust: Invoked by Alex to explain away his knowledge of how Zuko got his scar and had defeated Zhao in an Agni Kai. He claims that he overheard some Fire Kingdom soldiers gossiping about it while enjoying their shore leaves.

A Certain Magical Index

• A Certain Droll Hivemind: From "Guest Entry — Mikoto": Mikoto is annoyed that she can't hack into Judgment's communications as easily as normal, so she wonders if she should use a Fake High to get Uiharu to talk about how she set up security.
  [Kuroko's] precinct uses some really nasty frequency jumping algorithms and encryption tricks that makes it harder than Anti-Skill's stuff. Hmm. Note to self — buy Uiharu some rum and raisin ice cream and see if that has a placebo effect that gets her tipsy so she talks about how she implemented it. It's starting to get on my nerves that I can't reliably listen in.

Deltarune

• Incidence: The Purple Knight is prone to this, especially in moments where anger and frustration get the better of them. Ironically, though, he does remarkably well at keeping his mouth shut when he's at Kris' mercy.

Fullmetal Alchemist

• Son of the Desert: After Trisha's sister blabs that she started her period, Trisha finds herself being harassed by various unwanted suitors, as she is a batsheva believed to have a blessed bloodline.

Godzilla/MonsterVerse

• Abraxas (Hrodvitnon): One of Alan Jonah's men blabbing in fear for his life to Viv and San about "the others" gets him fatally shot by his commander. Given the guy's current circumstances of being trapped in a room with an angry kaiju, his blabbing only turned his life being cut short from a likelihood into a certainty, but still...

Harry Potter

• The Awakening of a Magus: After Ron proves that he's unable to keep silent about sensitive matters on his own, Harry magically swears both him and Hermione into secrecy.
• In Harry Is A Dragon, And That's Okay, Hermione accidentally reveals the existence of her time-turner to her friends while caught up in the realization that her usage of it while performing the Animagus sensitization ritual had the side-effect of making her Animagus form a deinonychus.

Hellaverse

• Pride, Envy, Wrath: While insisting that she's not homophobic, Lute makes an aside about how she's not that hypocritical, accidentally revealing her own sapphic inclinations.

How to Train Your Dragon

• Once There Were Dragons: This spurs the other former dragonriders to decline any invitations to join Hiccup and Astrid in visiting the Hidden World, reasoning that the less people know its location, the better. While nobody on New Berk would willingly betray the dragons, there's always the fear of somebody being tortured into a confession or Saying Too Much while drunk. Snotlout accidentally brought these fears to pass when he told Helga about the Hidden World, triggering the Oathbreaker War.

The Kingdom of Crooked Mirrors

• The Ghosts of the Old Castle: After getting drunk, Bar tells his companions about how much he despises Nushrok for having feelings towards Anidag, who's also disgusted'' by her father's interest in her.

The Loud House

• The Quest for Glory: The loser of the chess match overhears where the next clue is when Luan reads it out while they're still within earshot.

Love Hina

• For His Own Sake: Sarah pulls this off twice:
  • The first time comes when Seta's trying to convince Haruka to marry him. Sarah reveals that when Keitaro worked for him, Seta constantly grilled him for information, trying to learn everything he could about Haruka. Suffice to say, neither Haruka or Marumi are impressed by this revelation.
  • Later, Sarah gushes about how much fun she had at the Hinata Inn, especially since Keitaro, one of the only ones who ever tried to reign the Spoiled Brat in, got beaten up all the time. This convinces the teacher at her new school that she wouldn't be a good fit, recommending that Seta enroll her at the incredibly strict St. Clavius Academy instead.

Miraculous Ladybug

• The whole plot of Chat Blanc Against the World happens because Nino (as Carapace) casually drops in the middle of a joint patrol with Chat Noir that literally everybody else in the Miraculous team either knows or has figured out Ladybug's secret identity just as she knows theirs... everybody else but Adrien, that is. This triggers him hitting his Rage Breaking Point at being Locked Out of the Loop, getting Akumatized into Chat Blanc.
  • Marinette then accidentally reveals to the other members that she'd deliberately kept Chat Noir out of the loop because she was trying to prevent him from becoming Chat Blanc, which they promptly treat as a Self-Fulfilling Prophecy.
• Two Letters has this serve as the root of Marinette's anger at Alya. While she hoped her 'bestie' understood the importance of keeping their secret identities secret, Alya still went behind her back and let Nino know she was still active as Rena Furtive. Which was a major issue, as Nino has severe trouble keeping secrets, such as when he kept inviting everyone to join his 'secret society' against Hawkmoth.
• Weight Off Your Shoulder, a Recursive Fanfiction of Two Letters, has Future!Alix attempt to convince Marinette that she should stay the course and "suck it up", claiming that all her suffering will eventually be worth it. However, she accidentally namedrops Monarch, then mutters to herself about how she'd forgotten he hadn't stolen the Miracle Box yet. Marinette is naturally horrified to hear just how much worse things will get, and when Future!Alix refuses to reveal their enemy's Secret Identity because she prioritizes her timeline over preventing all the pain and anguish his reign of terror will cause, Marinette takes matters into her own hands.

My Hero Academia

• Bloodstained Heroes of Humanity:
  • When Izuku was younger, he accidentally informed Shirageki that he was born a vampire.
  • Later, he inadvertently outs Aizawa as a vampire to All Might, not realizing he was meant to keep that secret.
• In Cain, the school counselor at Aldera casually gossips with Katsuki about her sessions with Izuku, completely ignoring both confidentiality and how Katsuki is well known for brutally bullying him.
• Dekiru: The Fusion Hero!: After Izuku takes the Entrance Exam, All Might accidentally reveals to him that he knows he passed before Izuku got the official results. He promptly tries to Verbal Backspace out of it, but eventually relents.
• In Second Chances, Katsuki looks at Izuku's phone while he's hospitalized, and has an Oh, Crap! moment when he accidentally mentions how he got his phone to open.
• The Wrong Choice:
  • While informing Katsuki about the existence of One For All, Toshinori idly brings up that he just happened to bump into a 'Quirkless boy' shortly before meeting him, who'd asked if he could become a hero. He's blissfully unaware that Katsuki knows who that boy is, much less that Izuku is his favorite punching bag, and that he's just handed his ill-chosen successor a MASSIVE amount of ammunition to torment poor Midoriya with.
  • Katsuki immediately returns the favor by calling Izuku up just to taunt him with how All Might chose HIM instead of 'Deku'. While Izuku keeps the secret, Katsuki later decides to reveal One For All's existence on the internet, purely to keep rubbing that in Izuku's face and brag about his status.

Naruto

• Gem of the Eddy has Naruto revealing to his teammates that he's a jinchuriki early on due to Sasuke catching a slip of a tongue.
• In Little Uzumaki, Iruka snaps at some Gossipy Hens and accidentally reveals the identity of Naruto's mother. Without even missing a beat, they promptly start spreading rumors about who his father might be.

One Piece

• In Copycat Isn't a Compliment, a Recursive Fanfic for This Bites!, Cross' sickly ramblings cause the rest of the crew to zero in on Ami as his Secret-Keeper.
• This Bites!:
  • Inserted character Jeremiah Cross manages to keep his secret from the crew for a short while... up until he comes down with a case of Primal Cholera that, among other things, dissolves enough of his mental barriers to have him mention several things over the course of his few days of illness that were impossible for him to know. Once he's treated and finds that out in Chapter 12, his reaction is an immensely justified Oh, Crap!, but fortunately the crew forgives him after The Reveal two chapters later.
  • Vivi's blurting out Crocodile's identity is Lampshaded by Cross when she asks to be let in the loop of Secret Keepers.
    Cross: But pleeeeease promise me that you won't blab anything we need to keep secret to anyone who shouldn't know it?
    Vivi: [facefault] T-that was one time!

Pokémon

• Chosen One's Adventure with Legendaries: Upon realizing the identity of his father, Ash winds up blurting the news out to his friends following a close call.
• In Latias' Journey, the elder Wynaut reveals everything about the Lord Wobbaku statue, including how moving it would disturb the cloaking effect around the Mirage Isle, right in front of Jessie and James. This leads to Team Rocket successfully stealing said statue.

RWBY

• In Petals in the Ash, Cinder calls Blake "Cat" during a caffeine rush, accidentally revealing that she knows Blake is a faunus. Thankfully, nobody else picks up on it.
• Reignfall: May accidentally reveals to Mercury that she's Atlesian and attended Atlas Academy by complaining about how bad the Atlesian dorms are.

A Song of Ice and Fire

• Ned Stark Lives!:
  • Theon inadvertently informs Shae of how he's planning to take Casterly Rock, spurring her escaping to warn the Lannisters.
  • When Gendry is arrested at White Harbor, Arya reveals that she's married to him.

Star Trek

• Rey is said to be one in on arkanis it rains every day, as she always bring in whatever hot gossip she hears in the Outpost. When she mentions wanting to learn more about a nearby Jedi church, Tag warns her that she would just get herself killed by her too much talking.
  Tag: I mean if you know about this church, then soon the whole galaxy will, and anyone with a grudge against Jedi will come to Jakku and burn the whole bloody village down.

Tolkien's Legendarium

• The Heart Trilogy: In Heart of the Inferno, Kathryn attempts to talk her mate down at the Council of Elrond, only to accidentally blurt out his name and enrage the dwarves further.

Transformers

• Eugenesis: Hosehead ends up telling the time-displaced Optimus Prime exactly when and how he's going to die. Whoopsie-daisy.

Worm

• Great Grand-Uncle Schimmelhorn's Toolbox: Victoria and Amy specifically target Dennis when trying to figure out what happened to Shadow Stalker, figuring he's the most likely to let something slip in this fashion.

• In Cinderella, it's done subtly when the titular character becomes star-struck upon learning that the man she danced with at the ball was the prince and that he was looking for her. She becomes so distracted that she forgets to use discretion when preparing for his arrival (dancing and humming to herself) that she unwittingly tips off her stepmother that she was the mystery girl at the ball.
• This happened twice in Disney's animated film The Little Mermaid:
  • When Flounder tries to defend Ariel after she failed to turn up for her part in the concert, he inadvertently got Ariel into trouble with her father, King Triton, for going up to the surface by mentioning "seagull".
  • Sebastian, under the impression that King Triton knows about Ariel's love, blurts out about Ariel's recent visit to the surface, until he realises he spilt the beans to King Triton who then found out about Ariel rescuing Eric and her secret grotto. Sebastian regrets his mistake after Triton destroyed Ariel's secret grotto.
• The Magic Roundabout (2005):
  • After being captured and imprisoned by Zeebad, Dougal unwittingly mentions about the map whilst being questioned by Zeebad, giving the villain the information. Much later, Zeebad corners the group and forces them to give up the map after taking the first diamond.
  • Brian is another one after he unintentionally gave Zeebad the information of the third diamond due to him being blindfolded by his scarf when he landed on the roof of the drill train.
  Dougal: Hang on, Zeebad doesn't know the diamond's at the roundabout.
  Brian: Erm, that's not strictly true. Back there on the train, I was confused... and it just slipped out.
  Dylan: Brian, man!
  Ermintrude: Well, there's no use crying over spilt milk.
  Dylan: Easy for you to say.
• At the end of Puella Magi Madoka Magica, Homura talks to Kyubey in the new world remade by Madoka's wish about there being no more Witches born from despairing Magical Girls and subsequently how Madoka became Ret-Gone from everyone's memory save hers, now that she becomes the Law of the Cycle so that she could prevent their suffering. Unfortunately, her talking about it all gives the idea of there being an old system that promises to give more energy to delay the heat death of the universe in the first place, leading to the Rebellion movie and specifically how Homura herself became the Incubators' bait, since she's the only one who knows about Madoka in the remade world.
• Ratatouille: Emile is happy to keep Rémy's secrets about food at first, but he spills the beans that his little brother has prime access to fresh food. Cue hordes of rats showing up night after night.
• This is the entire plot of Resisting Enemy Interrogation, a 1944 production of the U.S. Army meant to teach airmen what not to do when captured by the enemy. The Germans at a POW camp dedicated to intelligence gathering receive a downed American air crew. They get them all to drop their guard and engage in casual conversation. The things that the American soldiers give away—one thoughtlessly blurts out that their bomber is based in Naples, another carelessly mentions the top speed of their plane, and another is such a Bad Liar that the Nazi officer rules out anything he says as a possibility—all add together enough to allow the Nazi commandant to figure out where the upcoming American bombing raid is headed.
• The SpongeBob SquarePants Movie: Plankton calls Squidward "Inspector Loose Lips" for his foolish mistake in deciding to confront him upon finding out about his evil plan, then threatening to take it up to King Neptune. This allows Plankton to prevent Squidward from doing this by activating the bucket helmets he's given to the entire populace to turn them into his slaves, with his first order being to subject the Squid to the same fate.
• Who Framed Roger Rabbit has the main character asking a few too many people where the detective's office is, allowing the bad guys to figure out where he's going.
• In Wish Dragon, Din's friend comes by his apartment to hand him his assignment and a warning from their teacher about skipping school. He says this in front of Din's mother and their nosy neighbors.

• Parodied in a flashback in Airplane!: The hero tells his girlfriend that he's going to be sent out on a mission soon. He then goes on to mention exactly where he's going, what he's going to be bombing, what time of day they'll be attacking, how high they'll be flying, and what direction they'll be coming in from. But he refuses to give her a rough estimate of when he'll be back from the mission because that's classified.
• Better Luck Tomorrow: Virgil is very chatty and has trouble keeping secrets. After he takes over as leader of their gang, the administration busts their test cheating ring because he went around the school bragging about it.
• Casino: Artie Piscano, the made man in charge of handling the Las Vegas skim, is a perfect example of this: he continuously whines to his mother about how he keeps spending money out of his own pocket going to and from Vegas ferrying the skim's cash with no refunding and other gossips about his fellow Mafia members and how they think he is an idiot (he is) in his business, which has been bugged by the FBI. The information he delivered with his ramblings, and the notebooks full of financial information of the skim he kept and the Feds founds when they raided his house, are single-handedly responsible for bringing the house of cards down.
• In The Fastest Gun Alive, Vinnie Harold would have just left Cross Creek after stealing the horses if young Bobby Tibbs hadn't boasted that Cross Creek had its own fast gun and showed him the two silver dollars George Temple had shot out of the air. This pushes the paranoid Harold into demanding a showdown with George, and he plans to burn the town down if he doesn't get it.
• In Hangmen Also Die!, Professor Novotny warns his daughter Mascha about this, noting that sensitive information can travel from one person to the next and quickly reach the ears of the Gestapo. When she replies that telling him shouldn't be a problem, he pulls out a dictionary to really drive the point home:
  "Definition of 'no one': not any, not one, not a single one, none!"
• Hidden in Silence: Dr. Hirsch isn't very close-mouthed about Fusia offering to hide him, and she ends up with half-a-dozen unplanned (although ultimately not unwelcome) queries for refuge from ghetto inhabitants Dr. Hirsch was indiscreet toward.
• In Shoot-Out at Medicine Bend, Nell gets Clegg drunk and causes him to blab all of his secrets: from the fact that he and his friends aren't really Brethren to the fact that King has a secret shipment coming into town.
• The Sum of All Fears movie has one nuclear scientist's mom giving away some information to Clark that allows him to find the terrorist's nuclear production area.
• Tales from the Darkside: The Movie: In the short story "Lover's Vow", a down-on-his-luck artist witnesses a gargoyle killing his bartender friend and the gargoyle makes him promise not to tell anybody what he saw. The artist manages to hold on for about a decade (although his art sees a resurgence when he begins to draw gargoyle art) but he cannot let go of the guilt unless he tells someone, so he tells his wife… which is the gargoyle. And as much as she loves him, the promise has been broken and she must do her part. She consoles him as she rips his throat out.
• Briefly comes up in WarGames, after David and Jennifer find out they accidentally hacked into NORAD and almost caused A Nuclear Error. After Jennifer gives a speech about how they won't be suspected if they act normal:
  Jennifer: Oh God, this is so unbelievable! Listen, do you think maybe I could call Michelle and tell her?
  David: NO, JENNIFER, DON'T CALL HER!
  Jennifer: Sorry. All right, I won't.

• In The Alice Network, the spy Eve becomes very good at getting men to tell her secrets. After the struggle it took to draw out René, she's surprised and amused at how easy it is to get her superior, Major Allenton, to tell her Captain Cameron's code name.
• The Ballad of the King's Jest by Rudyard Kipling, about a talkative man running into the Great Game and discovering that his boss in Kabul doesn't have so much patience that this could end well for him.
• In Gathering Blue, Kira tells councilman Jamison that her dyeing teacher claimed that the woods surrounding the village aren't actually full of "beasts." This gets Annabella killed since the council invented the beasts in order to scare the villagers.
• Harry Potter
  • Rubeus Hagrid in Harry Potter and the Philosopher's Stone does this several times. Trust him with your life, but not your secrets. The movie version even gave him a catchphrase relating to this: "I shouldn'ta told ya that!"
  • Bertha Jorkins in Harry Potter and the Goblet of Fire is no better at keeping secrets than Hagrid. As Sirius says it once: "She was a bit dim, but she had an excellent memory for gossip. It used to get her into a lot of trouble; she never knew when to keep her mouth shut."
• In Kollaa kestää, set in the Winter War 1939-1940, the Finns tap into a Russian communications line. The Russians talk so carelessly that they actually nonwittingly act as artillery observers for Finnish artillery.
• Jim Hickman was spoken of as being this by Mac McCullum in the Left Behind book The Mark when he accidentally lets slip to Nicolae Carpathia sensitive information shared in confidence by Nicolae to his close associates in the Global Community top brass, which leads to Ramon Santiago's death and Jim's own suicide.
• Nina Tanleven: In The Ghost Wore Gray, Baltimore unwittingly shares the secret of Captain Gray’s diary with the villain of the book. He admits later that he’s paid dearly for his mistake (the villain knocked him out and stole the diary).
• In Noob, Gaea had to stop playing her previous MMORPG because a friend of hers couldn't keep her mouth shut about the scams she was pulling on other players. That friend is playing her current MMORPG also, but Gaea's Manipulative Bastard habits where getting an embryonic Open Secret status by the time they ran into each other, making the info less sensitive.
• In N or M?, Tuppence pretends to have them by receiving coded letters from her fake sons to try and lure out the moles.
• The undoing of more than one of Parker's carefully planned heists in the novels of Richard Stark; usually to Parker's disgust.
• Professor Mmaa's Lecture: Professor Soul's Second Assistant, a termite who is a born snitch — literally. He's been born with auditory organs all over his body and is constantly registering so much input that he feels a physical need to dump this baggage out of his memory onto a number of interested termites.
• Tortall Universe: In Trickster's Queen, Sarai Balitang refuses to not speak out against the horrible injustices perpetrated by the Copper Isles' ruling family. The things she says are accurate, but the Rittevons are notoriously paranoid and touchy and have already arrested one very popular nobleman for trying to tactfully suggest that they not be quite so brutal, so it's a really bad idea. She also tells members of her social circle where there are anti-listening spells, another unwise move.
• While making the preparations for the expedition to the eponymous Treasure Island, Squire Trelawney blabs to anyone on Bristol who will listen about the massive treasure they seek. This despite being explicitly warned against this by Doctor Livesey and knowing there is a gang of pirates after the map and treasure. His crew gets massively infiltrated by pirates as a result.

• An episode of ER has two nurses talking about the two children of a patient who had been in an accident comforting each other... which ended up leading to Brother–Sister Incest. Unfortunately, they unknowingly were walking past the patient's husband, leading to a near-shooting incident (the father managed to calm himself down and came clean about what he had nearly done). The doctors were not pleased about the violation of Patient-Doctor Confidentiality and the incident it nearly caused.
• Hanna: Carmichael takes an interest in the Utrax program because he wants to use it to cover up a serious indiscretion of his. While drunk, he tried to recruit a friend into the Pioneer group and revealed too much information about their plans. The friend was repulsed by what Pioneer was doing and stole a document from Carmichael that could expose the entire conspiracy. If the leaders of Pioneer find out that Carmichael was the leak, he will be killed for it. When Marrissa finds this out, she blackmails Carmichael into covering up her and Hanna's actions.
• JAG: In "People v. Rabb", when Admiral Chegwidden says that what he's about to say is sensitive, Bud replies that My loose lips will sink no ships.
• Justified:
  • Boyd Crowder's latest heroin shipment was delayed and to placate his dealers he tells them that the shipment is arriving tomorrow evening. The next day one of the dealers is approached by a female junkie who offers to give him a blow job if he tells her when he will get new heroin. He obliges and sure enough, Boyd's shipment is hijacked and the men guarding it are killed.
  • One would think that a mob boss like Sammy Tonin knew how to keep his mouth shut about the murder he committed. However, Sammy has gone through a Villainous Breakdown and is high on drugs most of the time. He brags to his business partners about the murder and how he had help from a federal agent. One of those business partners gets arrested and trades that information to the cops.
• Once Upon a Time (2011): Do not trust Snow White to keep a secret.
• Barbra Jean from Reba has this reputation, and for good reason. Throughout the series, she's blabbed out things quite a few times, such as telling Reba's eldest daughter and son-in-law about her youngest daughter's decision to move in with Reba's ex-husband — even after promising not to blab.
• On Turn this is a rich source of information for spies on both sides.
  • When Abraham strikes up a conversation with some Hessian soldiers, he easily finds out that they are going be to quartered for the winter in the town of Trenton. George Washington uses that information to attack the unprepared Hessians and defeat them at the Battle of Trenton
  • A wandering minister turns out to be a British spy. He exploits the fact that the American soldiers will talk freely with a man of the cloth and he passes any information he gleams to the British. In turn, he is discovered because a British officer talks about this in a public tavern where an American spy overhears it.
  • Robert Townsend became part owner of a tavern specifically so he would be able to eavesdrop on British officers talking too openly after they had a few drinks. His business partner is a Loyalist but uses the trope himself to get scoops for the newspaper he publishes. Robert is thus able to sneak into his partner's office and read a story that is supposed to be published in a few days after a surprise British attack has been launched. Robert passes the information to the Americans who attack first and rout the British.
• The Wire: Randy Wagstaff gets caught up in tragedy due to a series of incidents of loose lips; Little Kevin asks him to set up Lex for an ambush, and later tells Randy that Lex is dead and disappeared. Randy later gets into trouble at school and to get out of trouble, tells the vice principal about the murder. After he talks with police, Herc then lets slip to Little Kevin that they know from somebody that he was involved, and Kevin immidiately asks if it's Randy. Little Kevin is then killed by Marlo for involving an extra party and telling him too much, and while he won't have his men retaliate against Randy directly, Marlo orders the word to be put out that Randy is a snitch, which results in him being first beat up at school, his home burned, and ending up at the bottom of the pecking order at the group home.
  • Sergei accidentally spills the Greek's body disposal MO in a casual phone conversation with White Mike that leads the Major Crimes Unit to link the dead Turkish sailor to him.
  • subverted when the team investigates Prop Joe's organization. Joe's nephew Drac speaks way too openly on the phone, and the team try to set him up to be promoted to get him talking too much higher up the chain, but that never happens. Meanwhile, Cheese is extremely cautious on the phone, and the team think they struck gold when the catch him talking about shooting Dawg on the phone. However, Dawg in question was his fighting dog, and Cheese had performed a Mercy Kill. While Cheese's friend did also shoot the person responsible for Dawg's injury, he is savvy enough to keep his mouth shut after the police overplay their hand.

• "Secret" by The Pierces (which became the opening theme for Pretty Little Liars) paraphrases the quote at the top of the page: "Two can keep a secret if one of them is dead".
• "Loose lips sink ships" is in the chorus of "Slip Of The Lip" by Ratt.
• A line from Taylor Swift's "I Know Places":
  Loose lips sink ships all the damn time
  Not this time.

• At one point in the Star Wars Radio Dramas, Princess Leia is trying to get information out of an Imperial-connected nobleman and arguing about the Empire's love of weapons programs when she accidentally lets slip the phrase "Death Star". Since that's still an extremely classified code name at the moment, he's immediately suspicious that she knows it. She tries to play it off as a coincidental metaphor, but the jig is up and violence ensues, eventually leading to the events of the movie.

• BlazBlue has this trope used to rather devastating effect against its invoker. After a fight, Hazama tells Makoto, in no uncertain terms, about Relius Clover's "random and untoward" interest in her before making an attempt on her life (and getting frozen by Jin for it). He really should have picked a better compliment in hindsight. ^Why?Hazama sends Relius after Makoto, and he eventually 'escorts' Jin out of Ronin-gai as bait. Bang's keen-eyed disciple spots the masked creeper and reports to his superior, who passes the info to Makoto — with this information and Relius' mention in the report on Noel, she chooses to send Bang after Jin (and Relius) while she attends to Noel and Tsubaki. The long-term consequences are still being explored, but without Relius to restrain her, Hazama's plans fell apart soon after.
• Parodied in Danganronpa 2: Goodbye Despair when the green tutorial text mentions if some segments seem too tough, it tells the player they can change the difficulty if necessary. Then tries to withhold the info that the player would have to reset the class trial by doing that, even as the text box clearly shows the particular information being said.
• In Daughter for Dessert, Moe Mortelli lets slip several clues that the protagonist is, or is about to be in, serious trouble that would upend his life. This leads to the protagonist breaking into Mortelli’s office to find out what the detective knows but isn’t telling him.
• In Double Homework, Henry lets the protagonist’s surprise party slip to him while everybody’s still planning it.
• Fallout: New Vegas includes propaganda that's related to the common loose lips sink ships posters. At Helios One, it includes the "telling your wife" scenario, and "telling your drinking buddies", showing the route on how information reaches the Chinese spies.
• Mass Effect 3: The Alliance News Network twitter updates on the Reaper invasion of Earth, which included details on where civilians were able to get military protection so they could escape Earth. Emily Wong realized too late that the Reapers had been reading the tweets to find out where the evacuation point was so they could attack it.
• Rise of the Third Power: The two times he goes on a date with Brooke, Rowan gets drunk and talks about his party's activities. Since Brooke is the Arkadyan spy, Sparrow, this leads to Arkadya always being one step ahead of the party.
• A bizarre meta example: a War Thunder player claiming to be a Challenger 2 tank commander leaked classified military manuals to prove that Gaijin had misrepresented the tank in-game as being weaker than it really was. Mere months later, someone leaked the manual for the LeClerc tank to prove a similar point. Gaijin eventually had to beg people to stop posting classified secrets in a public forum for video games, out of a very justified fear that these confidential manuals would end up in unfriendly hands and that they would be on the hook for the consequences. The plea didn't take, as classified details about the F-16 were leaked after the release of the 'modern jets' update, and a player in China leaked confidential ammunition handling documents to prove that Gaijin had wrongly underpowered Chinese ammunition.

• What a Legend!: Mei's bard lover meant well in turning her story about the king's betrayal of a mercenary company into a song, but it inevitably gave away the fact that there were survivors — which got the survivors on the wanted list, and the bard killed.

• hololive:
  • In a meta sense, this has sometimes come up. After the debut of Hololive Japan Generation 2, Cover Corporation has since made previous experience in content creation a requirement for applying to them. This means that many members of Hololive were streamers prior to joining, and a number of them still stream independently of Hololive using their old accounts. Because of this, on occasion when streaming using these original accounts they sometimes slip up (most often switching to their Hololive talking styles like referring to themselves by their Hololive names in the third person). Generally they're very careful about anything that could actually cause problems, however there have been some cases.
    • Prior to the debut of the fourth generation, the one who would become Kiryu Coco was streaming and accidentally let slip she'd be working for Cover in the near future. She jokingly asked her viewers not to report her to Hololive, but shortly after the stream in question was privated.
    • This was the reason given for the termination of Uruha Rushia on 24th February 2022, with Cover Corp.'s official notice specifically mentioning her leaking information to outside parties. Rushia at the time was the most superchatted member of Hololive, regularly pulling in wave after wave of red (i.e. the highest level) superchats from viewers, but that wasn't enough to save her.
    • On 16th January 2024, Yozora Mel had her contract with Cover Corp. terminated due to likewise leaking confidential information. Mel's case is an even better example of this trope than Rushia's, as according to her ^note  Via an alternate alter ego she used before she joined Hololive, as by that point she could no longer access her official Hololive accounts she was speaking to a friend and accidentally let confidential information slip, and that information later got out. In an example of It Can't Be Helped, she accepted that she had to go, and was at least allowed to post a farewell message on her Twitter account. She also received messages from the likes of Cover Corp president Yagoo and prominent staff member A-chan expressing their thanks to her for everything she'd done, adding to the sense that had it been possible Cover would not have gone so far as to have terminated her contract. It should be pointed out that she had no less than 3 sponsored streams scheduled, so her termination did in fact affect Cover financially (meaning they'd have reason to try to avoid going that far), but she'd breached her contract and there was no other option.

• In El Goonish Shive, Mr. Verres berates Grace for "recklessness and loose lips" for her actions during "The Secret of Sam" storyline.
• Girl Genius: Zeetha has an unfortunate habit of blurting out important information at inopportune moments. "They're looking for the Wasp-Easter!"
• Unsounded : The Red Cost: Nora tells Mr. Giz "Loose lips twist nips" when he brings up the rumors of the new construct program she's heading, obviously hoping for some information on the military constructs which Nora isn't going to be sharing.

• Dina Marino and Siria Ashen accidentally reveal on Instagram Live that Siria committed financial fraud and identity theft in order to be enrolled into Seoul National University.
• Wikipedia has an entry explaining the dangers of putting sensitive information (or at least, information that can come back to bite you in the ass) on Wikipedia.

• Dr. Horrible's Sing-Along Blog: The eponymous Ineffectual Sympathetic Villain has a blog, which he uses to talk to his fans about various things he's done and his plans for future schemes. This backfires on him in Act II when it turns out his viewing audience includes Captain Hammer and the LAPD.

• BoJack Horseman: When investigating Sarah Lynn's death, Intrepid Reporter Paige Sinclair hits upon the idea of trying to get info from attendees of the AA meetings she was said to have been in. Maximilian is skeptical, since the second 'A' stands for 'Anonymous' after all, but Paige claims that people just wouldn't be able to resist gossiping about celebrities. Sure enough, they find one that remembers Sarah Lynn being there, along with a horse whose name he couldn't remember (BoJack, obviously), but he did remember the name of the girl from New Mexico the horse talked about, leading to Paige's next move: to interview Penny.
• In Central Park, Season 1 "Rival Busker", Paige is able to get a tip about Bitsy's activities when Doug sees Bitsy greet Dmitry at her hotel and Dmitry tells her he looks forward to seeing Bitsy's secret ballroom, which Bitsy points out it's not a secret anymore since he said it out loud. After they enter the hotel, Doug calls Paige and tells her about it.
• DuckTales (1987): The episode "Spies In Their Eyes" centers around Donald Duck involved with an experimental remote control Navy submarine that Scrooge's company built. Since "Loose beaks cause leaks" Donald has to keep it secret, but ends up stealing it when he becomes hypnotized due to a woman's Hypnotic Eyes.
• Looney Tunes: In "Plane Daffy," an American carrier pigeon is being seduced by Hatta Mari and starts blabbing out military secrets after drinking a Mickey-slipped drink.
• The Loud House:
  • This is Lincoln's flaw in "Brawl in the Family". After Lori and Leni get into a spat over buying the same exact dress, he goes to their room to help them resolve their argument, but he accidentally ends up revealing a Dark Secret one thinks of the other, which reignites the fight. He does it again at the end of the episode.
  • In "Breaking Dad", when Lynn Sr. calls Rita to tell her that the daycare closed for the day due to one of the toddlers flooding the place by clogging the toilet with a whole diaper, Rita tells him she can't watch Lily due to her spending the day at the dentist office filling all five of the Fox Quintuplets' cavities, which could cancel Lynn Sr.'s plans to attend the Cowbella Music Festival. While Rita is treating Pam, the sole female of the quints, she lets it slip that there's only enough nitrous oxide (laughing gas) for four of them and Pam becomes worried she won't be getting gassed for her treatment.
• In the My Little Pony: Friendship Is Magic Season 5 premiere, Pinkie Pie spills the beans that some ponies miss their cutie marks when visiting a small village where every pony has their cutie mark taken away, prompting the village leader to remove their cutie marks.
• Norman McLaren of the National Film Board of Canada was even less subtle in Keep Your Mouth Shut with a cackling Nazi skull thanking all the blabbermouths in Canada for giving away such good intelligence.
• The Private Snafu short "Spies": Snafu brags about how he'll never tell the secret information he knows, but he carelessly drops hints which are eagerly picked up by hidden spies.
• The Proud Family: In the episode "Thelma and Luis", the kids find out that a nursing home LaCienega's Papi was sent to is actually a front for an illegal okra plantation, and Suga Mama is the only one of the adults who believes the kids, at which point they break in to rescue him. While Suga Mama and Papi go on the run to avoid its evil administrator, who is now hunting him down, and the Boulevardezes tell the Prouds what's really going on, Penny lets its slip that she, LaCienega, Dijonay, Zoey and Sticky helped Suga Mama break him out.
• One episode of StarCom: The U.S. Space Force revolves around this. When Cadet Flash Moskowitz learns that he'll be accompanying Dash and Slim on a trip to Mars and Saturn, he boasts about it on the academy message boards, getting the attention of Shadow Force spies. After later learning that they're transporting a prototype oscillation hyperthruster to Saturn, Flash happily shares this classified information with the first person to bump into him on the street: a disguised Shadow Force general.
• In Trollz, Topaz bragging about where the Trollz are going for vacation leads to more and more people being told, and soon Big Bad Simon catches wind of it.

• World War II:
  • As mentioned above, the Trope Namer is the American slogan reminding people to be careful what they talk about in public, lest Axis spies pick up valuable clues. Another poster showed a Nazi putting a puzzle together that said "The Convoy Sails for England Tonight". The caption was "bits of careless talk are pieced together by the enemy."
  • One of the British counterparts to this was "Careless Talk Costs Lives," although variations of "Keep mum" were also used.
  • The Soviet counterparts were the "Don't blab!"◊ and "A blabbemouth is a treasure for the enemy!"◊ slogans, with the latter having remained a common saying in Russian language up to present days.
  • In Nazi Germany, there was the slogan "Feind hört mit!" ("The enemy listens in!").
  • World War II Japanese sub-hunters habitually set their depth charges to a depth shallower than the diving capacity of most US submarines — until Andrew Jackson May, a Congressman, mentioned this in a press conference. The Japanese immediately started setting their depth charges deeper, likely costing several submarines and their crews because one of their elected representatives couldn't keep his mouth shut.
• Journalist Geraldo Rivera in early 2003, while Rivera was traveling with the 101st Airborne Division in Iraq during a Fox News broadcast, Rivera began to disclose an upcoming operation, even going so far as to draw a map in the sand for his audience. The military immediately issued a firm denunciation of his actions, saying it put the operation at risk, and nearly expelled Rivera from Iraq.
  • Parodied by The Daily Show, which saw this as Rivera getting overexcited about establishing his Intrepid Reporter credentials.
    Stephen Colbert: He's the only reporter out here who's got the cojones to walk it like he talks it! He can't be constrained by concern for the safety and security of men who have invited him to join them at great risk to both themselves and their military objective! If he gets everybody killed, so be it. He's not gonna pussy out.
  • As a general rule, war correspondents are supposed to avert this by saying things like "This is John Smith, reporting from somewhere in X" rather than "This is John Smith, reporting from City Z in the nation of X" unless the story being reported is the fact that they just took Z, to keep anyone on the other side who is listening in to the broadcast to figure out where their enemies are.
• News of the impending attack on Goose Green during the Falklands War was released by the British government and broadcast on the BBC World Service while the troops were still advancing on the town (and hadn't yet been detected by the Argentinian forces).
• Nondisclosure agreements (NDAs) is what supposed to keep people from talking in regards to business deals or other sensitive information. If the person breaks the NDA, they can be fined, lose their job, or get sued, depending on the circumstances.
• People that work as Public Relations (or PR) are tasked with making sure that whatever is said about their company doesn't break any rules or paint the company in a bad light, even if it's the truth. Interviews are usually done through a PR or with someone who has a PR on standby to make sure that person doesn't say anything damaging. This is also a legitimate reason why social media accounts belonging to employees are monitored. People have been sacked for speaking out on social media in a way that brings bad publicity to the company.
• In 2015, a localizer for Nintendo of America appeared on a video game podcast. One of the topics the person talked about was why Nintendo doesn't bother localizing certain games. Not only did the localizer break their NDA, but they said that Nintendo doesn't localize certain games if the company thinks it won't make them money. While it is the harsh truth, it makes Nintendo sound like they prioritize money over what the fans want. The localizer was promptly fired.
• Tom Holland has gotten a reputation for spilling secrets for movies he's in. It's gotten so bad that he wasn't allowed to read the whole script for Avengers: Infinity War. The directors, the Russo brothers, joke about how allowing him to improvise his death scene was the only way to keep him from spoiling it. He spoiled that he was staring in the film adaptation of Uncharted by posting a picture of himself playing the games "for research" to Instagram. He even spoiled the plot of Jurassic World: Fallen Kingdom to Chris Pratt despite Pratt being the star of the movie. This habit of his even got lampshaded in the second trailer for Spider-Man: Far From Home, which began with Tom telling the audience that the trailer had spoilers for Avengers: Endgame.
• Among the Yanks with Tanks, Article 101 of the UCMJ (Uniform Code of Military Justice) makes the improper use of a countersign^note As if divulgating passwords a capital offense due to this trope: after all, divulgating the password to a military base can means that an enemy unit can infiltrate it, and the password to a server might means all the informations contained there are compromised.
• After CIA agent Richard Welch was murdered in Greece on 1977 by Revolutionary Organization 17 November (17N), the Intelligence Identities Protection Act made a crime to reveal someone is a covert agent.
• A Ukrainian man was arrested after posting a TikTok video of military vehicles parked near a shopping mall that was later blown up by Russians.