Characters wearing clothing they're way too old for is always funny. But's it's even crazier when they decide to wear clothes meant for literal babies! Bonus points if they act like a baby too while in the clothes.
Basically, a character (usually a petite adult, but a child can attempt this too) dressing themselves up and pretending to be an infant for ludicrous reasons attaining to the plot. Keep in mind that, sometimes, this trope may have happened against a character's will thanks to their partner-in-crime's schemes.
A possible scenario has said tiny character needs to infiltrate somewhere, but the problem is, how can they do that if they're so small in stature, and therefore reaching any windows would be difficult? The solution: Passing themselves off as a Doorstep Baby! And when their unwilling victim takes them inside, Hilarity Ensues.
- In this commercial for Cookie Crisp, Cookie Crook disguises his dog, Chip, as a baby and himself as his mother to trick Cookie Cop into looking after Chip to distract him so he can steal Cookie Crisp. This plan fails because Chip howls "Coo-oo-ookie Crisp!" upon seeing the titular cereal, allowing Cookie Cop to see through his and Cookie Crook's disguises.
- One Piece: One member of the Donquixote Pirates, Senor Pink, is a middle-aged man who dresses like a baby, with a bib, a pacifier, an undersized tank top and swimming trunks. His backstory explains why he dressed like that: his wife and baby got caught in an accident, and the former became a vegetable while the latter died. When he tried dressing like a baby to make his wife react, she reacted with a light smile. Since then he keeps wearing baby outfit.
- The Loud House fanfiction The Nightmare House involves Lisa having a nightmare where she's put in a diaper (and also a tee, but tees are more for everyone) and sent to daycare.
- The My Little Pony: Friendship Is Magic fanfic Pound and Pumpkin Cake's Adventures (and Misadventures) in Potty Training:
- At one point, the twins trick Pinkie Pie into putting a diaper on so they can treat her like one of them.
- Apple Bloom once steals Pound's diapers and puts them on, trying to remember her parents, who died when she was a toddler.
- Discussed when Flurry Heart claims that she wants to wear diapers forever.
- In the final chapter, the twins are now six years old and pretending to be toddlers, dressing in diapers.
- In an unnamed fanfiction of The X-Files, Scully is dressed in a childish dress by a villain who wants to mesmerise her into thinking she's a kid. Later, a woman thinks Scully really is a child (although she's still 5'2) and puts a diaper on her.
- In Despicable Me, three minions disguise themselves as humans to go to a store. One of them, Phil, dresses as a baby.
- Kronk's New Groove: Several senior citizens dress up like babies in order to convince Kronk's dad that they're Kronk's kids.
- Stretched in Who Framed Roger Rabbit: Roger's coworker Baby Herman is a literal baby toon, but his personality is that of a middle-aged man. For his job portraying a baby, he dresses and acts like a baby on set.
- Zootopia: Nick's assistant, Finnick (an adult fennec fox), helps him out by dressing up as a mute baby and pretending to be his son.
- Little Man stars a dwarf jewel thief disguising himself as a Doorstep Baby in order to get a diamond back. The film has been accused by several people of ripping off the below "Baby Buggy Bunny". Animation historian, Jerry Beck went so far as to write a short article listing similarities. It even won a Razzie for it.
- In the Good Luck Charlie episode, "Appy Days", Charlie wants Gabe to play with her baby doll, but Gabe does not want to play with her, and just wants to be left alone. When he tells Bob that he is sick of Charlie and calls her doll stupid, Charlie overhears and has her feelings hurt. Gabe asks Charlie what he has to do to make it up to her, and she says, "You baby!". In the following scene, Gabe is dressed in a baby bonnet and sitting in Charlie's stroller, much to his ire, especially since Teddy films this particular moment for her video diary.
Teddy: Well, Charlie, I don't know how you got him to do that, but thank you. We'll be enjoying this for years. (To Gabe) Now say, "Good wuck, Charlie!"
Gabe: Do you want me to spit up? 'Cause I'm not afraid to go there.
Teddy: Cranky baby.
- In one of Billy Barty's "David Hafowitz" sketches on Short Ribbs, involving a car seat for infants, Patty Maloney portrays "Florence Nightmare", dressed as a baby.
- One famous story about giant Fionn MacCumhail features this trope. After getting in a fight with another giant he cannot defeat, he runs home to hide. His wife disguises him as a baby. When the other giant discovers that even the babies are huge and (depending on the version of the tale) incredibly strong, he flees.
- In the Dinosaurs episode, "Out of the Frying Pan", Baby becomes a celebrity thanks to the Myman Frying Pan commercials he stars in. This leads to Fran imagining a Bad Future where Baby, as an adult, had let fame go to his head, got arrested, and blamed her for it. The adult version of Baby shown in Fran's imagine spot is shown to be wearing a yellow shirt and a diaper, much like the infant version of Baby.
- Sesame Street:
- In the series' 35th Anniversary special, "Elmo's World: The Street We Live On!", Elmo asks the children how Cookie Monster eats cookies. He then asks two babies, one of which is really Cookie Monster dressed as a baby.
- In a "Smart Cookies" sketch, The Crumb disguises himself in a baby bonnet to fool Cookie Monster so he can steal the teething biscuit of the baby that the Smart Cookies are babysitting.
- In one episode, Baby Bear's grandma visits and thinks he's a literal baby, so she puts him in a bonnet. She wants to put him in a diaper, too, but he stops her.
- One of the title character's disguises in Axe Cop is as a baby. A six foot tall axe wielding baby.
- One Val and Isaac strip has Space Dredd shapeshift into a baby to ambush her target (who sees her as a tasty morsel). The final frame has her unable to change back, but refuses to admit it so Isaac can help.
- In "Arthur's Baby", D.W. puts diapers on all of Arthur's dolls to practice changing diapers.
- In "Arthur's Cousin Catastrophe", Arthur has a flashback to a time when his cousin put baby clothes on him.
- In "Two Minutes", when Tommy finds out that he's two minutes older than Timmy, he starts bossing Timmy around. Timmy decides to get back at Tommy by acting like a baby, wearing only a diaper and Tommy's red kerchief. Tommy is horrified and calls for his grandma.
- Batman: The Brave and the Bold: Zigzagged when crime boss Babyface mounts a jailbreak. He's hiding his hulking frame in a stroller to fool the guards, but is actually wearing a three-piece suit beneath the disguise.
- The 1988 version of Beany and Cecil featured this trope at the end of "Framed Freep", where Dishonest John's punishment is being treated like a baby by the Freep, complete with being forced to wear a diaper and a bonnet.
- In the CatDog episode, "Adventures in Greaser-Sitting", Cliff makes Cat and Dog babysit his infant niece because Lube got his head stuck in a bicycle. When Cliff's Niece runs away and Lube comes to take over, having gotten his head unstuck, Cat dresses Winslow as a baby and gives him to Lube. At first, Winslow does not want any part in this plan, but he soon comes to enjoy Lube taking care of him, and makes Cat treat him the same way after Cat returns Cliff's Niece at the end of the episode.
- In the Chip 'n Dale: Rescue Rangers episode, "Dirty Rotten Diapers", a series of robberies results in Thaddeus, an adopted baby being returned to the adoption agency by every couple whose house was robbed. It is later revealed that Thaddeus is really a dwarf disguised as a baby who runs the robberies.
- Dexter's Laboratory: After receiving an "average" score on a test, Dexter renounces his genius image and searches his closet for "average" clothes. The newest outfit he owns prior to inventing his lab is a pink baby getup.
- The Dog City episode, "Adventures in Puppy-Sitting" features Puppy-Face Felson, a thief disguised as a baby hired by Bugsy Vile to steal Zsa Zsa Gbark's Hope on a Rope diamond. When Ace Hart is tasked with looking after Felson, he believes Felson to be a real baby, and endures some slapstick trying to protect him, getting out of it without major injuries and leaving destruction in his wake. The overall experience terrifies Felson, who condemns Ace as a Babysitter from Hell and confesses to his crimes just to get away from him.
- Donald Duck:
- In "Officer Duck", Donald pretends to be a Doorstop Baby in order to arrest Pete.
- "Modern Inventions" has Donald crawling into a stroller at a museum and pretending to be a baby during a gag.
- In "Don's Fountain of Youth", Donald and his nephews are on vacation in Florida, but the boys are more interested in their comic book than in sightseeing. When Donald finds a spring with a sign saying that it was mistaken for the legendary Fountain of Youth, he decides to play a prank on the boys by putting on a baby bonnet and acting like a baby, making them think he was de-aged by the fountain.
- In the Donkey Kong Country episode, "Baby Kong Blues", when Donkey Kong and Diddy babysit Baby Kong, Baby Kong ends up in King K. Rool's lair, and K. Rool takes a liking to him, even going as far as not to trade him for the Crystal Coconut, which he's been after for most of the series. To keep Candy and Dixie from finding out they lost Baby Kong, and as part of Donkey Kong's plan to get him back from K. Rool, Donkey Kong dresses Diddy as a baby against his will.
- In the DuckTales (2017) episode, "Storkules in Duckburg!", Louie films a commercial for his Harp-B-Gone business, starring Webby as the husband, Huey as the wife, and Storkules as their baby child, complete with the bib, bonnet, and diaper. Bad "Bad Acting" ensues.
- In the Garfield and Friends episode, "Bouncing Baby Blues", a human baby winds up in Garfield and Odie's shopping cart on their way back from the supermarket. When the baby runs away, Garfield dresses Odie as a baby against his will to take the real baby's place until he can find him. The baby's mother is not fooled when Jon gives her the disguised Odie, but Garfield manages to find the real baby and return him to her. At the end of the episode, the disguised Odie whispers something in Garfield's ear, which results in Garfield saying, "No, I will not change you!".
- Goof Troop:
- In "And Baby Makes Three", Max, P.J. and Pistol think that Peg is having another baby, so they decide to have P.J. pose as a baby so he can drive Pete up the wall and make him not want another child.
- In "Leader of the Pack", Max messes with a bully named Duke after being asked how he can win the love of Max's cousin Debbie by tricking the brute into dressing up like a baby.
- Jakers! The Adventures of Piggley Winks: An episode has Ferny dressed as a baby and lying in a stroller in order for Piggley to get past a bully.
- The Jetsons: "Little Bundle of Trouble" has Astro becoming suspicious of a "lost baby" who is really a jewel thief in disguise.
- Kappa Mikey: In "Mikey's Place", in the subplot, Lily is caught red-handed showing hatred toward babies, so Ozu forces her to take care of a baby for one day to regain LilyMu's reputation. When the baby crawls away, Guano is forced to take his place. Guano comes to enjoy being treated as a baby, though.
- Looney Tunes:
- "Baby Buggy Bunny" is about a dwarf gangster named "Babyface" Finster who, after a clever bank robbery, loses his ill-gotten gains down Bugs Bunny's rabbit hole, forcing him to don the disguise of an orphan baby to get it back.
- In "Gorilla My Dreams", Mrs. Gruesome Gorilla believes Bugs Bunny, who is revealed to have travelled downriver in a barrel, to be her baby. At first, Bugs is against the idea, but he agrees to be her baby to keep her from crying. When he does, she dresses him in a bonnet and a diaper.
- In the The Looney Tunes Show episode, "The DMV", Daffy unsuccessfully tries to get Bugs to wear a diaper when they go to the movie theater because babies get into the theater for free. In the epilogue, Daffy dresses himself as a baby in an unsuccessful attempt to see a free movie.
- The Loud House:
- In "Changing the Baby", Clyde is unhappy because his best friend Lincoln is hanging out with his (Lincoln's) baby sister Lily instead of him. Clyde tries to win Lincoln's attention back by dressing as a baby.
- In "Cover Girls", Lincoln disguises himself as Lily when Pop-Pop wants to talk to her on video chat.note When Rita finds out that her children have been deceiving Pop-Pop by disguising themselves as each other, she makes each one of them wear the clothes they're wearing right now for the rest of the day as punishment. At first, Lincoln, who is still disguised as Lily, thinks it won't be too humiliating, since all he will be doing that day is watching ARGGH! with Clyde, but then it is revealed that Clyde invited Lincoln's entire class to watch the show with them. Cue Lincoln's classmates laughing and taking pictures of him.
Lincoln: Oh, poo-poo!
- In "The Whole Picture", Lincoln dresses himself in a diaper as part of his plan to re-stage some old baby photos that he accidentally deleted off his computer.
- In "Potty Mouth", as part of their plan to prevent Dr. Shuttleworth from hearing Lily saying the D Word, Lincoln and his sisters disguise Lisa as Lily and swap them out. Unfortunately, this doesn't go as planned, as Lisa ends up displaying her Child Prodigy talents, and when Luna tells her to act like a one-year-old, Lisa decides to poop her diaper.
- In "Room and Hoard", Lincoln finds his first shirt, his bib, and a beanie that says "#1 Baby Boy", and to prevent his parents from getting rid of them, he starts wearing them. When the Loud kids give their stuff away at the end of the episode, Flip and his raccoon are seen wearing them.
- The New Woody Woodpecker Show: In "Baby Buzzard", Buzz Buzzard reads an ad in the newspaper that Woody is starting a babysitting service for rich and famous couples. Buzz dresses himself in a bonnet and booties and acts like a baby as part of his plan to get Woody to babysit him so he can rob his house when he's not looking.
- In the Peg + Cat episode "I Do What I Can: the Musical", Ramone dresses as a baby because he's acting in a play and playing himself as a baby.
- Private Snafu: In "Spies", one of the Japanese spies is disguised as a baby. Snafu, naturally, fails to notice.
- The Ren & Stimpy Show: In "The Big Baby Scam", a starving Ren and Stimpy exploit the benefits of living as babies by switching lives with a pair of babies, which of course includes wearing diapers.
- In the episode, "Angelica's Birthday", Angelica decides to act like a baby to avoid the responsibilities that come with getting another year older. She dresses herself in a purple shirt and a green bonnet from the dolls in her own bedroom, as well as a diaper from the babies' diaper bag.
- In the episode "Regarding Stuie", Stu has amnesia and thinks he's a baby, so the babies put a sheet on his crotch for a diaper.
- In "Party Animals", Didi's cousin, Bucky comes to a costume party at Angelica's house that Drew and Charlotte host. Bucky's costume consists of nothing more than an adult-sized diaper, which leads the babies to think that he's a giant baby.
- The New Scooby-Doo Mysteries episode "Happy Birthday, Scooby-Doo" had Scooby dress like a baby to try and remind his friends that it is his birthday, unaware that his friends are pretending to forget because they have a surprise party planned.
- In The 13 Ghosts of Scooby-Doo episode "A Spooky Little Ghoul Like You", Scooby and the gang try to stop Vincent Van Ghoul's wedding to Nekara by pretending to be Van Ghoul's family. Scooby, Shaggy and Scrappy pretend to be Vincent Van Ghoul's children by wearing diapers and bonnets.
- Scooby-Doo! Mystery Incorporated featured a villain called Crybaby Clown, whose gimmick is that he was a Monster Clown who dressed and acted like a baby.
- In the The Simpsons episode, "Mr. Plow", Barney is shown handing out fliers for the Lullabuy$ baby furniture store, wearing a diaper and bonnet, in the middle of winter. He then loses the diaper after saying that things can't get any worse...
Barney: Come back, diaper! Come back! (turns to face his mother) Hi, Ma.
- In an episode of The Smurfs, Gargamel the evil wizard pretends to be, not only a baby, but a Smurf as well, to infiltrate the village.
- In the Spongebob Squarepants episode "Squid Baby". Squidward thinks he's a baby due to a head injury and is put in a diaper.
- In the The Super Mario Bros Super Show! episode, "Two Plumbers and a Baby", King Koopa, under the alias of King Goo Goo Ga Ga Koopa, guards a Fountain of Youth that turns anyone who falls into it into a baby (which happens to Princess Toadstool, and later King Koopa himself in the episode). King Koopa's Goo Goo Ga Ga Koopa alias has him dressed in a bib, a bonnet, and a diaper, despite him being his normal adult age (at least until he falls into the fountain near the end of the episode).
- TaleSpin: In "The Bigger They Are, The Louder They Oink", as part of her plan to retrive truffles from the Island of Zibaldo, Rebecca disguises a large ugly pig (not-so-affectionately named "Hogzilla" by Baloo) as a baby in order to get him past a security checkpoint that doesn't allow pigs.
- In the Teenage Mutant Ninja Turtles (1987) episode, "Four Turtles and a Baby", as part of Shredder's plan to capture the Neutrino baby that the Turtles are babysitting, he sends Bebop and Rocksteady to the Pretty Baby Photo contest at the Channel 6 Studio, with Rocksteady disguised as a baby, and Bebop disguised as his mother.
- In an episode of Third And Bird, Muffin convinces a reluctant Mr. Beakman to pretend to be a baby for a game of house.
- In the short, "Ruffled Ruffee" from the Tiny Toon Adventures episode, "Music Day", Buster attends Ruffee's concert dressed in a diaper and a green bonnet as part of his plan to sabotage the concert as retribution for tossing his electric guitar and speakers (which had earlier inadvertently interrupted the concert) into his burrow and slapping him forcefully. This comes into play near the end of the short when Ruffee reaches his Rage Breaking Point and tries to yell at the disguised Buster, but instead yells at a human baby dressed in a nearly identical way and gets beaten up by the baby's father as a result.
- Tom and Jerry:
- "Baby Puss" has Tom being dressed up and treated as a baby.
- In "Baby Butch", Butch disguises himself as an orphaned waif so he can raid Tom's fridge.
- In Winston's Potty Chair, the titular Winston thinks about his mother telling him that someday he won't have to wear diapers. He then imagines everyone in the park wearing diapers, and quickly decides that they look better without them.