A character with a big mouth says something stupid or, better yet, self-incriminating, often with the subject of their commentary standing nearby or, better yet, right behind them.
The trope name comes from the phrase "to put your foot in your mouth" (also playfully referred to as "foot-in-mouth disease", a pun on the very serious livestock illness "foot-and-mouth disease").note
Compare Shutting Up Now for a similar reaction. Can lead to any of the following: Change the Uncomfortable Subject, Digging Yourself Deeper, Did I Just Say That Out Loud?, That Came Out Wrong. Sometimes more than one.
- Latvia of Axis Powers Hetalia is prone to this, which is a very bad thing when Russia is constantly hanging over your shoulder. Often closely followed by Lithuania or Estonia's "Latviaaaaaaaaaaa!"
Latvia: I do feel safer in his hairy arms.
Estonia: You should really keep your mouth more closed.
- Cowboy Bebop: Spike is very aware of this trope.
Open foot, insert mouth.
- Done in epic fashion in Death Note when L asks Light how, as a detective, he would go about trapping Kira, Light's secret Serial Killer alter-ego. Once Light has given L his answer, L "praises" him by pointing out that while it usually takes professional investigators several minutes to even come up with an answer to that question, Light immediately responded with an answer that a serial killer talking directly to the investigators would give.
- Tsurubami Kamome from Medaka Box actually gets kicked in the mouth twice for doing this too often. Not that it hurts him.
- A particularly bad example occurs in the new Jughead series of the Archie Comics (2015): Archie agrees to come camping with Jughead, but almost immediately gets distracted and takes them towards a girls' camp instead. When Jughead complains, Archie responds "I won't apologise for being a normal guy!" Jughead, being canonically asexual in this continuity, is stunned speechless for a moment. Archie immediately apologises, but Jughead is uncharacteristically thrown and seems genuinely hurt—it's not just that Archie implied he wasn't normal, but the whole situation of his friend seemingly half-abandoning him for girls is a common fear among asexual and aromantic people, that they'll be left behind once their friends start dating and be left alone.
- In Chrysalis Visits The Hague, The protagonist Estermann says the following to Lyra, a pony (It Makes Sense in Context):
Estermann: Because as far as Im concerned, a pony's only good to be ridden and sliced up for sausage. How the hell am I supposed to make myself a picture of one's 'inner workings'?
- Child of the Storm has it Played for Drama in the sequel when Maddie, whose social skills are somewhat lacking, picks a very unfortunate moment to tell Jean that her boyfriend is cheating on her (having just found out via her own Telepathy). Specifically, when said boyfriend was meeting her parents. Jean, unsurprisingly, blows up, having been under a lot of pressure to begin with, and ends up taking it out on Maddie, who is miserable because she didn't want to hurt Jean and was only trying to help.
- It's also played seriously earlier on in the sequel in the case of Harry's friends after he returns to Hogwarts — having been through an epic Trauma Conga Line, he really does not have the patience for teenage idiocy anymore. Thankfully, some counseling and the passage of time helps him cool off a bit.
- Played for Drama in the The Loud House fanfic A Dark House: Inadequate when Lori, in a fit of anger over some broken perfume, snaps at Lincoln that sometimes she wishes she didn't have a brother. While she quickly realizes what she said and is clearly upset, Lincoln runs off in tears and locks himself in his room, even shouting that no one cares about him when Lori and some of the other girls try to talk to him.
- Elecktrum's Narnia Fics are full of this trope. One fic revolves around it completely, and another has a chapter revolving around the similar phrase "eating crow." Her OCs and minor characters also get into the act, especially where Edmund is concerned:
- Tumnus unintentionally insults Edmund by implying that Edmund had worked for the white witch in "The Conscience of the King".
- In "Black Dwarfs, Blue River" an overzealous faun angrily tells Edmund regarding the persecution of families of some satyrs who fought on the witch's side that the wives and children (who did not fight for the witch) were "Sons of traitors [who] deserve what what they get." Edmund responds coolly: "so what will you call my sons?" Oops.
- And then there's Ilano's Right in Front of Me moment in "They Also Serve".
- In the Back to the Future fanfic Homecoming, George, not knowing about the age gap between Doc and Clara, asks where "Mrs. Brown" is. He's mortified when he finds out that Clara is Doc's wife, not his stepdaughter, and apologizes profusely.
- In Kira Sweetheart Light has one of these moments when he discovers that L has been abused in the past.
Light: WHO did this? Give me their name!
- The My Little Pony: Friendship Is Magic fanfic "The Model Caretaker" Has Fleur de Lis struggle with this in the first half of the story, especially when Fluttershy is about.
- My lesbian life with Monster Girls: Monster Yurisume: In chapter 129, Yuisu, overworked and stressed out, chews out Haru for changing her mind about getting printer paper when Yuisu asked and forgetting to tell her, which leads to her declaring that Haru never takes her requests seriously, citing the fact that Haru dyed Hakuto pink after Yuisu literally begged her to stop the prank war as proof. All Haru can think of to say in response is, "That was different. I mean, I had already ordered the hair dye", which really sets Yuisu off.
Yuisu: Oh, so that's how it is. My heartfelt plea is worth less than a bottle of hair dye.
- The New Look Series has several examples of this trope.
- In the prequel to Respawn of the Dead, Heavy accidentally insults Medic a few times. But, to be fair, it's pretty clear that Medic is only insulted by being told he sounds like Greta Garbo because he has no idea he was practically quoting her.
- In the Rivals Series Viktor can't help but unintentionally offend Yuuri through unwanted advice or very poor wording which doesn't help Viktor's attempts to get Yuuri to at least tolerate him. Then Viktor starts to develop the opposite problem so Yuuri would at least speak to him.
- From another MLP fanfic, The Rise of Darth Vulcan: Artful Dodger is discussing showering with Eiderdown and starts speaking before thinking.
You could literally see the words traveling from his mouth, to his own ears, and from thence to his brain. His eyes went round for a second. "Once. One. At a time, that is. Not that there isn't enough room for two. Heh. I mean—- I'll go first, that way you can take your time. Afterward. By yourself." He literally shoved his own hoof in his mouth to shut himself up. He bit down on his hoof for a second then spoke around it. "G-g-give you time to, uh, pretty yourself up afterward...."
- This Bites!:
- During the scene in the palace baths, after Cross finishes telling Nami he has too much respect for her to peep on her, she manages to call him up to the wall to talk to him, only to give him an eyeful of Vivi instead. The first thing Cross comments on is whether she's dedicated with the hair dye. Vivi's stool, meet Cross's cranium.
- When Cross wakes up from Enel's initial attack and sees Conis, he makes a statement about how he wished he could've seen Enel's face when Luffy kicked the crap out of him, thinking that he missed the whole arc... not realizing he was only knocked out for a second and a very unamused Enel is right next to them.
- Since Usopp never leaves the crew in Water 7, while acting as Sniperking to try to pretend to be someone braver, he essentially states that 'Usopp' deserted from the mission of rescuing Robin without any significant reason. Luffy is not pleased by the implications.
- In My Huntsman Academia both Izuku and Nora are frequently guilty of this. The former's tendency comes from his social awkwardness, while the latter's comes from her Cloudcuckoolander tendencies. For instance, the following conversation Izuku has with Weiss:
Izuku: [when Weiss asks what he isn't good at] W-W-Well, I'm not good with t-talking to people! I get really nervous, and I can't even talk to girls sometimes without just going blank.
Weiss: [snorting] You're doing a fine job with me at the moment.
Izuku: Yeah, but I don't see you as a girl. [Beat as Izuku goes sheet-white]
Weiss: Explain. Now.
Izuku: I-I-I-I didn't mean it l-l-l-ike that Weiss! I m-mean I just see you as a teammate! I know you're a girl! A smart, nice, pret-
Weiss: Compliments later! Speak!
Izuku: [curls up into a ball as she looms over him] B-But it's easier to just see my teammate! When I think about it, I get all n-nervous and shakey, so it's just simpler that way! Please don't be mad!
- SAO: Mother's Reconciliation: In chapter 9, Kyouko ends up doing this when she tells Asuna that since her brother turned out successful because he listened to her and followed her orders, Asuna should just "stop wasting her time and theirs, and do what she says." This ends up pissing Asuna off so much that she runs away from home.
- While discussing Su's desire to up the security at the Hinata Inn in The Beast That I Am (to stop the Ogre if she shows up again), Keitaro tries to dissuade Kitsune by pointing out that eventually Su will turn all of that security on him.
Kitsune: But it ain't a big deal when bad stuff happens to you! It's me and the other girls I'm worried about!
Keitaro: Wait... what did you just say Kitsune?
Kitsune: I said it's me and the other girls I'm worried about! It don't matter when bad stuff happens to -! Well, what I mean was that...well, you're indestructible. You and I both know that!
Keitaro: Uh... yeah.
- In Neither a Bird nor a Plane, it's Deku!, Professor Stein gushes over the possibility of being a godfather when Hisashi is discussing his sudden vacation. He quickly apologies when Hisashi screams about how he's infertile. He does end up becoming a godfather when the Midoriyas adopt a baby Kal-El.
Stein: Congratulations, Hisashi, my boy! You're going to be a great father, I just know it! Can I be the godfather? I've always wanted to be a godfather, Hisashi!
Hisashi: Yeah, well that's not going to happen, because we can't have any kids! [spits a stream of fire out of frustration]
Stein: Um, well, now that you've finished whatever that was and I've finished removing that foot from my mouth, allow me to apologize, again.
- Dragonball Evolution: When Chi Chi reveals that she knows of the existence of ki and states that her name doesn't mean she's an idiot, Goku proceeds to embarrass himself this way.
Goku: Right. Right. 'Cause there's a lot stupider names than Chi Chi. I'm not saying that Chi Chi's a stupid name. I'm just saying that it's not normal. Ah. But normal is overrated. I'm not saying that you're stupid or overrated. I'm just- I'm gonna stop now.
- Peter Rabbit: When Bea decides to greet her new neighbor who just moved into the McGregor mansion, she makes insulting comments regarding the late McGregor without even suspecting that the newcomer became the mansion's new owner by being the late owner's next-of-kin.
- In Short Circuit Howard theorizes the potential danger of having their laser-armed robot roaming free. The stereotypical Indian guy, Ben, hasn't really grasped the concept of discretion.
Howard: What if it decides to melt down a busload of nuns? How'd you like to write the headline on that one?
Ben: Nun Soup?
- X-Men: First Class: During the climax, Charles desperately tries to reason with Magneto and calm him down after the combined Soviet and American fleets fire on the X-Men after seeing their power, insisting that they're all good, innocent men who are Just Following Orders. This ends up really setting Magneto off, since he's a Holocaust survivor and the Nazis Magneto had previously confronted said just that to excuse their actions.
- Nina Tanleven:
- In The Ghost in the Third Row, when one of the costumes for the play is damaged, one of the people involved says that "Does it make sense to think it was done by a ghost? Or is it more likely that it was done by one of our local looney birds?" He remembers too late that the script writer Alan Bland, who's right on stage with him, had spent time in a mental hospital the year before and starts to blush and stammer. Nine and Chris are confused at the time, but learn why he reacted like he did the next day.
- In the same book, after learning about Alan's history, Nine unwittingly tells the man's writing partner Paula Gellar that "You guys are crazy!" after finding out how much material they'd written and discarded while writing the play and music, then looks horrified when she realizes what she just said. Paula figures out what she'd learned, and gives her a patient lecture about everything Alan had gone through and how much effort and courage it'd taken for him to put his life back together.
- In the Fortunes Of War books, the lead character has a tendency to stick her foot in her mouth, and lampshades it on herself in Dreadnought! when she makes a snarky comment about a particular phaser design to Mr. Scott only to learn that it was his design.
Piper: [to Sarda] Do me a favor, will you? Just reach down my throat and pull out my vocal cords.
- Taran does this constantly around Eilonwy in The Chronicles of Prydain, which just fuels their UST. He grows out of it (mostly) after some Character Development.
- Buffy the Vampire Slayer
- Spike does this often when he's trying to court Buffy.
- Invoked by Buffy in "Dopplegangland" when she tries to apologize to Willow (not realizing she is talking to Willow's alternate universe vampire double) for an unfortunate comment earlier in the episode, saying, "You know how my foot likes to live in my mouth."
- Coupling: A form of Cannot Talk to Women, by Jeff: just about every time Jeff talks to a woman, he manages to do this. For example, this exchange occurs just when things seem promising:
Lynda: I like kissing, don't you?
Jeff: Oh, yeah! Especially the tongues part. I love getting all that extra tongue. You know, sometimes I eat really cold ice cream just so that my tongue goes numb and it feels like someone else's... But then we all get lonely sometimes.
- Doctor Who: In "The Day of the Doctor", the Tenth Doctor has a bad habit of doing this while talking to Queen Elizabeth I, repeatedly saying terribly offensive or regrettable things under the assumption she was a Zygon duplicate. It gets them married.
- On ER, Carol's new boyfriend Shep makes some insensitive comments about the suicide attempt patient was brought in, suggesting that "she didn't really mean it" because she took pills as opposed to a more lethal method. Carol snaps, "I really meant it", referring to her own suicide attempt a year earlier in which she herself overdosed on pills (and as a nurse, she would certainly have known what would be a fatal amount) and storms off. A flustered Shep asks if she was serious and the mass Death Glare from everyone else confirms it.
- In Firefly, Simon does it virtually every time he tries to have a conversation with Kaylee.
- In one episode of The Fresh Prince of Bel-Air, when Uncle Phil makes a remark that offends Vivian, Will quips "I've always known you're a hungry man, Uncle Phil, but both feet?".
- In one episode of The Golden Girls, Blanche had an epic one. She meets and asks out a man she met in a bar, not realizing at the time (since he was sitting down) that he was blind. When he comes to pick her up for their date, she enters the room, saying things like, "Aren't I the prettiest thing you've ever seen?" and "What's the matter, are you blinded by my beauty?" She finally takes a good look, sees his cane, and stops in her tracks. Sophia directly addresses it, saying, "Want a glass of water to wash down your foot?"
- JAG: Lt. Bud Roberts falls victim to this fairly often, especially in the pilot movie whenever dealing with Lt. Caitlin Pike. His case of Foot-in-Mouth Disease is particularly unfortunate given that his original job is Public Affairs.
- Kamen Rider Dragon Knight: Kit says this trope word to word after unknowingly hurting Chris.
- Referenced fairly often on M*A*S*H. In one case, BJ claims Charles has "put a whole shoe store" in his mouth." (That example, interestingly, was incorrect, as Charles had fully meant to offend everyone.)
- A Moody Christmas. In the first episode Dan mistakes Cora for a door-knocking Red Cross volunteer because of her shirt, and donates some money. It turns out she is his cousin's new girlfriend, isn't a volunteer, and designed and hand-made the shirt herself.
- Jimmy Palmer is very prone to this. He does not seem to have heard the old adage that "a closed mouth gathers no feet". His foot tasting episodes routinely escalate to Digging Yourself Deeper territory.
- DiNozzo runs afoul of this trope from time to time as well.
- In Sherlock, we have Molly.
Molly: How's the hip?
Mrs. Hudson: Oh, it's atrocious. But thanks for asking.
Molly: I've seen much worse. But then I do post-mortems.
- Star Trek: The Next Generation: During the 3rd season episode, Hollow Pursuits, Capt. Picard accidentally calls Barclay by his unofficial nickname Broccoli. Data tries to put a positive spin on the situation by referencing psychology but really only makes the situation worse.
- Schitt's Creek: All the Roses do this occasionally, but Johnny Rose does it all the time. Often, Johnny has every right to assume something he's wrong about, but he still gets blamed and guilted. Examples include when he assumes Alexis is pregnant, when he assumes Ted's mother has a crush on him and when he assumes Patrick's parents know their son is in a relationship with David.
- The cover for Robert Sherman and Al Larsen's album "Smash Flops" (containing such bon mots as Columubs, You Big Bag Of Steam and Watch World War III On Pay TV) has a Virgil Partch drawing of a conductor directing three male singers, each with their foot in their mouth.
- Peter from The Four Gospels does this constantly, saying something that he thinks is smart only for Jesus to show him how completely wrong he is. He finally breaks this habit somewhere in the middle of Acts.
- Also from The Bible: James the Lord's brother spends the middle part of chapter 3 from his own epistle to explain how dangerous the tongue really is.
Even so, the tongue is a little part of the body and boasts great things. See how great a forest a little fire kindles. The tongue is a fire, a world of evil. The tongue is among the parts of the body, defiling the whole body, and setting the course of nature on fire, and it is set on fire by hell. (James 3:5-6)
- Cartoonist Ron Tandberg often depicted former Victorian Premier and Hawthorn Football Club president Jeff Kennett literally doing this when he made a gaffe.
- Happens during a story arc in Zits, when Jeremy says increasingly thoughtless things to Sara (first "Your freckles help cover your zits" and "What's it like having divorced parents?"), the word balloons for which immediately turn black with white letters and linger in the air.
- Occurs in Danganronpa V3 during the second class trial after Monosuke accidently reveals some important information regarding the current murder to the students. His siblings weren't too happy about it.
Monotaro: Way to put your foot in your mouth.
Monophanie: His foot? Monosuke just unhinged his jaw and swallowed his entire leg!
- God of War (PS4): During the final boss, Freya tries to soothe Baldur, remarking that she knows that "how he feels hasn't changed." Not the best thing to say to a guy who's gone insane from a hundred years of sensory deprivation because of her actions.
- In Tales of Symphonia, if you have Colette cook for the party after Lloyd reveals that she can't taste or feel anything, you can sometimes get a skit where Kratos will complain that the food was cooked too hot and over-seasoned. He immediately realizes his mistake and quietly tells her to ignore him.
- Code Name: Hunter: Gypsy stuffs both feet, up to her knees in when called to the commander's office by Queen Moraine. She's not in trouble. Yet. One of the readers lampshaded this in the Shout Box.
- Dan and Mab's Furry Adventures:
- Aaryanna has the bad habit of invading the dreams of her boyfriend Merlitz, but when she tried to convince Dan to embrace his Cubi's cultural heritage, she commented that's nothing better for a cubi than simply invade other peoples' dreams... and she said that within Merlitz's earshot.
- The title says all...
- Abel, when he has to explain his Cubi mark on his back (neither he or his mother were aware that he was a cubi at the time, but his theory of how it got there doesn't please his mother).
- Dan is a master of this trope, and he is aware of this.
- Lorenda does this epically here.
- Dragon City:
- Rachel makes a demeaning comment over the Ex-mayor, Donningan, saying that he was arrested for being ugly in the wrong place. Too bad that his grandaughter was within Rachel's earshot.
- Sam would do the same mistake when he talked an explicit language to Rachel within Jonas' earshot.
- Beatrix isn't a master in keep compromising secrets to herself.
- The Fox Sister: Alex has a talent to say just the wrong things to Yun Hee.
- Niomi is busy repairing the waste-water recycling plant. The toilets will work and you can get a drink.
- Not the best thing to say to an uplifted dog (well, wolf).
- Sam Starfall tries to convince Florence not to trust Winston too quickly, only to accidentally confess to being everything but trustworthy
- Niomi is busy repairing the waste-water recycling plant. The toilets will work and you can get a drink.
- Grrl Power has Sydney do this constantly when Peggy's artificial limb comes up. For bonus points, said missing limb is the leg below the knee, and the page's title is "Open mouth, insert foot to just below the knee."
The Rantz; Sydney, think of things NOT to say, then DON'T say them.
- Gunnerkrigg Court: In "Questions and Answers", Mort the ghost says Annie is "attractive", then starts backpedaling and trying to explain he didn't mean that kind of attractive, and concludes by turning himself into a gravestone with a "foot -> mouth" pictograph.
- Ménage à 3: Clueless geek Gary is prone to this sort of error. See here for one, lampshaded, example.
- A defining trait of Flux from morphE, to the point that the comic introducing her was even named Open Mouth to imply this very trope.
- Paranormal Mystery Squad: Apparently, Stephanie's been around the block a few times 'cuz she seemed way too familiar with "Inspiration Point". She not only failed to cover it up, she wound up confirming it by proudly admitting it to Agent Lisbon:
- A Running Gag in Schlock Mercenary is the multiple creative variations used to call someone (usually Tagon, but he was by no means the only guilty party) out when they said something particularly embarrassing to or about another character while in earshot. It doesn't get mentioned as frequently in more recent strips as it did early on, but still pops up from time to time.
- Stand Still, Stay Silent: One character describes the sound of the Danish language. With a pair of Danish soldiers right behind him.
- In Tales of the Questor, Quentin tries to compliment Meribeth on something other than her breasts.
- Done at least twice by Grey O'Shea in Terra, though the best one is also the first. See page 130 where he crossed it with Right Behind Me.
Simmons: [referring to Grey's rescue of Alex and Rick] C'mon, I saw that one of the officers was female, and a cute one at that—I know you, Grey.
Grey: Her?! Please, she's way too uptight. I don't have time for girls like that.
Simmons: What, you think you even stand a chance?
Grey: Give me a break. She may have an attitude, but if I wanted her, I could have her by the end of the night.
Alex: Hm, I'll take that bet.
- Twokinds: "Red" has recently started running afoul of this trope. Winds up running into Digging Yourself Deeper territory.
- The Whiteboard:
- In this strip Pirta and Swampy get into a brief discussion of his nickname. After Swampy asks about her name in an idiot moment for him, he comments that he can skip the appetizer, as he'll just chew on his own foot.
- In this strip, a customer that's been hassling Pirta for a date is asked if he'd be okay with the situation were their positions reversed, and she were trying to get him to cheat on his girlfriend. He accidentally lets slip that he'd be fine with cheating on his girlfriend Jenny for a date with Pirta. He winds up thrown bodily out of the store after being beat up by Pirta for his troubles.
- Questionable Content: Lampshaded when Faye belatedly realizes she shouldn't be asking the Shell-Shocked Veteran combat droid Bubbles why she doesn't fight.
Faye: I'm just crammin' my foot further and further down my throat, aren't I.
Bubbles: A Cronenbergian ouroboros, indeed.
- Happens often in Aladdin: The Series with the title character.
- Family Guy: In "Road to the North Pole", Brian, while accompanying Stewie at the mall to meet Santa Claus, sees Quagmire with a bald child and assumes that he has a nephew. He learns, to his utter horror, that it's actually his niece, who has cancer and is bald from chemotherapy.
Brian: Oh gosh, I... I didn't know! I'm so... I'm so sorry!
Quagmire: Oh, you're sorry? F-For what? That waiting in line is such a catastrophe, that you'd rather destroy the confidence of a 5-year-old cancer patient?
Brian: Aww, come on. I-I didn't know she was dying.
Quagmire: Who said anything about dying?!
- The Flintstones: Fred did this on many occasions.
- Gravity Falls: In "The Stanchurian Candidate", Grunkle Stan insists on speaking his mind rather than use the speech Dipper and Mabel wrote for his mayoral campaign against Li'l Gideon, but he can't even complete a sentence without revealing his amoral nature.
- In Justice League Unlimited, Batman and John Stewart are talking about relationships when John idly mentions Bats and Wonder Woman being together. Batman starts explaining that, while he admires her as a friend and a teammate, going any further isn't really in the books before he comes to realize that, oops, she's right behind him.
- This happened in The Life and Times of Juniper Lee: The titular character calls her crush a "total babe with the hair and the cute smile" when he's standing Right behind her. She quickly realizes this. In fact the full sentence is:
"Just because Marcus is a total babe with the hair and the cute smile, doesn't change the fact that he's standing right behind me does it?"
- In My Little Pony: Friendship Is Magic episode "No Second Prances", after Starlight Glimmer calls out Twilight Sparkle on her paranoia towards Trixie, Trixie begins to gloat and calls winning over Starlight a victory. This hurts Starlight and she wants an explanation. When Trixie tries to explain that she really was her friend and beating Twilight was just a bonus, Starlight's so hurt by this, she ends up running off.
- Steven Universe: Pearl is in fine form in "The Test", first accidentally revealing that the Sea Spire mission was a test, then digging herself deeper when she desperately tries to rectify the situation. Her Oh, Crap! expressions throughout the whole thing are priceless.
- Happens to The Hipster in the Tex Avery short "Symphony In Slang" when he's put on trial for skimping out on a restaurant bill, and every time he opens his mouth, he puts his foot in it. Like everything else in the cartoon, this is illustrated.