History Main / KiddieKid

In more justified cases, the kid in question has not had a conventional upbringing (e.g. they're orphans, homeschooled or sheltered), causing them to have a naïve outlook. They may also act younger than their age due to being neurodivergent. ValuesDissonance may also play a part: in Japan, for example, childishness is considered cute (at least in girls).

* ''WesternAnimation/{{Braceface}}'': In the episode "Act Your Age" 14-year old Sharon dates a boy named Pablo and it turns out he's only 12 years old. However at several points in the episode he behaves like someone younger than that, he wears shoes with velcro (which most boys his age don't) and his 13th birthday party has clowns and loot bags (this last one is even lampshaded by Sharon, who mentions that her brother, who's younger than he is, doesn't do this). Most boys that age would think they were too old for something like that. However, this is justified to show how much younger he is than Sharon.

* ''WesternAnimation/KingOfTheHill''. : Bobby Hill in later episodes. Even though he is supposed to be 14 years old, he occasionally acts very childish. This is mainly a case of DependingOnTheWriter; in some episodes he is fairly intelligent and mature and in others he is incredibly whiny, foolish, and immature. The 13th season has some of the worst offenders, with episodes like "Master of Puppets" and "Reborn on the Fourth of July".

** Downplayed with 11/12-year-old Lincoln Loud, who mostly acts his age, but owns a stuffed rabbit named Bun-Bun, which he cares for with an affection most kids his age would have outgrown.

* ''WesternAnimation/MaxAndRuby'': Max starts out at 3 and speaks in one-word sentences. As a 4-year-old he speaks in complete sentences but not in fluent English. He is the only kid in his class unable to do so.
* ''WesternAnimation/MiraculousLadybug'': Chloé Bourgeois is 14/15 and very much behaves like she was 6, still carrying around a teddy bear and believing in things such as Santa Claus and cooties as well as having the temper of a literal spoiled child. Most of this stems from her MissingMom and her father constantly enabling her behavior. Neither parent, however, is willing to own up to this.

* ''WesternAnimation/TheOwlHouse'': Luz Noceda is a high school-aged teenager and has the rowdiness, wonderment, and imagination of a child at least in their elementary years. She has even played with dolls at her current age before and is interested in action figures. Justified, as it's revealed that her fixation with her fantasies partly stems from years of social isolation from her peers, pressure from society's expectations and, most importantly, [[spoiler: from her grief following the death of her father at young age]].

** Bart Simpson in several later season episodes is often seen acting far younger than a ten year old, most likely as a result of having his BrattyHalfPint characterization {{Flanderiz|ation}}ed. This is emphasized by Marge and Lisa buying him easy reader books and videos meant for very young children.
** Milhouse had never seen chapter one of WesternAnimation/FindingNemo until he came across it by accident, when asked to [[Recap/TheSimpsonsS11E9GriftOfTheMagi bring a toy to school]], he chooses one that's for three-and-under.

* ''WesternAnimation/SouthPark'': This is part of what makes [[TheSociopath Eric Cartman]] such a terrifying (and [[BlackComedy hilarious]]) AntiHero. Despite being around nine or ten years old, he is ''extremely'' juvenile at times--he throws violently angry temper tantrums when he does not get his way, is obsessed with sweets (in one episode, he claims to have psychic powers, then demands ice cream and cookies in exchange for using his "gifts" to help the police), and still loves to play with stuffed animals and dolls. Part of the reason is [[FreudianExcuse his parenting]]--his mother Liane endlessly coddles him and treats him as her "little poopsykins," so he doesn't have to grow up (although she does gradually [[GrewASpine get better at disciplining him]]).

* ''WesternAnimation/StevenUniverse'': Steven has a VagueAge for the first season and a half, but in "Steven's Birthday" is revealed to be turning fourteen. His MuggleBestFriend and LoveInterest, who's not even thirteen but is more mature, is shocked. Aside from the fact that he still sleeps with a teddy bear and generally acts like he's under eleven, Steven also [[OlderThanHeLooks looks quite younger]]: because [[HalfHumanHybrid his mother]] was [[TheAgeless an ageless alien]] whose species have their physical forms match their mental ages, this ended up applying to Steven as well, with his dad showing Connie a scrapbook showing that Steven hasn't physically aged since he was eight. ''[[WesternAnimation/StevenUniverseFuture Future]]'' would finally have a more mature (but emotionally unstable) Steven who finally looks his age (at that point, 16).

* ''WesternAnimation/MonstersInc'': Zigzagged with Boo, who is implied to be about two since she's potty trained but clearly still a toddler. Her vocabulary is more like an eighteen-month-old consisting mosting of babbling, but her drawing skills are rather advanced for a two-year-old.

You turn on the TV and start watching it. Apparently, some child actor is guest starring. But wait a minute. How old is his character? He says he's X, but he's acting like X minus 5. What kind of 14-year-old gets real excited over a balloon? 10-year-olds don't ([[PeripheryDemographic usually]]) watch Creator/NickJr! Wait, a 12-year-old [[StillBelievesInSanta still believes in the Tooth Fairy]]? Why is a 15-year-old still playing with toys? To put it simply, that character is a Kiddie Kid.

* ''WesternAnimation/{{Rugrats}}'': Downplayed for Chuckie. He's two, and while he mainly behaves like a two-year-old, the only word he can say [[BabyLanguage to the grownups]] is "No".

* Jeffy Jeffy from ''WebVideo/SuperMarioLogan'' is a teenager, yet plays with children's toys and acts like a hyperactive five-year-old. Not to mention, he still wears diapers.

* ''WesternAnimation/{{Braceface}}'': In the episode "Act Your Age" 14-year old Sharon dates a boy named Pablo and it turns out he's only 12 years old. However at several points in the episode he behaves like someone younger than that, he wears shoes with velcro (which most boys his age don't) and his 13th birthday party has clowns and loot bags (this last one is even lampshaded by Sharon, who mentions that her brother, who's younger than he is, doesn't do this) Most boys that age would think they were too old for something like that. However, this is justified to show how much younger he is than Sharon.

* ''WesternAnimation/BeavisAndButthead'': For a teenager, [[DumbBlonde Beavis]] is shown to be quite immature. In "[[Recap/BeavisAndButtheadS5E01HeldBack Held Back]]", he enthusiastically joins the other kindergarteners in finger painting and coloring. And in "[[Recap/BeavisAndButtheadS6E09Babysitting Babysitting]]", he enjoys himself by playing the toys that are meant for the little children, who he's supposed to be babysitting.
%% * Gene Belcher from ''WesternAnimation/BobsBurgers'', is this combined with CloudCuckoolander.

* ''WesternAnimation/SonicTheHedgehogSatAM'': This version of Tails is intended to be ten years old, which would make him older than his game counterpart, who is stated to be eight. However, he acts as if he were junior to [[VideoGame/SonicTheHedgehog1 his game counterpart]]; Tails is not allowed to be a Freedom Fighter for his own safety, which closely matches the way adults would [[SurprisinglyRealisticOutcome realistically]] treat a ten-year-old, but it still doesn't explain his immature personality. He also calls Sally "Aunt Sally" despite there only being a slight age gap between them.

* ''WesternAnimation/BeavisAndButthead'': For a teenager, Beavis is shown to be quite immature. In "Held Back", he enthusiastically joins the other kindergarteners in finger painting and coloring. And in "Babysitting", he enjoys himself by playing the toys that are meant for the little children, who he's supposed to be babysitting.

* ''WesternAnimation/MaxAndRuby'': Max starts out at 3 and speaks in one word sentences. As a 4-year-old he speaks in complete sentences but not in fluent English. He is the only kid in his class unable to do so.

* ''WesternAnimation/SonicTheHedgehogSatAM'': This version of Tails is intended to be ten years old, which would make him older than his game counterpart, who is stated to be eight. However, he acts as if he were junior to [[VideoGame/SonicTheHedgehog his game counterpart]]; Tails is not allowed to be a Freedom Fighter for his own safety, which closely matches the way adults would [[SurprisinglyRealisticOutcome realistically]] treat a ten-year-old, but it still doesn't explain his immature personality. He also calls Sally "Aunt Sally" despite there only being a slight age gap between them.

* Deconstructed in ''VisualNovel/UminekoWhenTheyCry''. The fact that 9-year-old Maria acts younger than she is causes her to be bullied in school, and infuriates her mother to the point of abuse. In the first four arcs, other characters often [[LampshadeHanging lampshade]] how young she acts despite her age.

** All of the kids said "and" without pronouncing the D at the end even when they were teenagers. Most kids in real life outgrow this type of speech impedement after they finish kindergarten.

* PlayedForDrama in ''Fanfic/InfinityTrainBlossomingTrail'': Hop is usually depicted as a pre-teen who is capable of handling himself and is off on his own adventure to be a great Trainer. However, by the time we cut back to him when he's been stuck in The Fog Car (aka ''VideoGame/SilentHill''), he's somehow mentally regressed to a six or seven-year-old boy, acting affectionate and childlike to [[VideoGame/SilentHillHomecoming Alex Shepherd]] to the point he's asking for bedtime stories and drinking chocolate milk and butter cake before bed. This is presumably due to what Walter and Henry wish to enact for a ritual, needing seven people to embody certain aspects, and Hop represents "Delight".

* ''WesternAnimation/AsToldByGinger'': Macie turns into one in the episode "Family Therapy" after her parents start treating her like a four-year-old after forgetting her birthday. She starts to enjoy playing on a Rocket Tykes Swingset and a My First Jungle Gym, going to the local SuckECheeses, has her thirteenth birthday party at a petting zoo (with kiddie-style decorations), and even starts dressing more like a four-year-old. Ginger notes that Macie is liable to get bullied if this continues, and repeatedly tries to fix the problem. Macie gets annoyed at Ginger's intervention (and ends up being proven right when the most popular kids in school think the petting-zoo party is [[TrueArtIsIncomprehensible some sort of post-modern statement]] and dub it the coolest thing they've ever seen). In an interesting subversion of the trope, the episode ends with Macie admitting that she ''knows'' this behavior is far too juvenile for her: she's just making up lost time with her parents, and assures Ginger that she'll be talking with them about treating her like a teenager soon. Given that she ends up back to her old self, this presumably works.

* In the ''Literature/DiaryOfAWimpyKid'' books, Greg's friend Rowley is one -- although he's in early-middle school, he prefers to hang out with six-to-eight-year-olds, be it holding a birthday party at the local SuckECheeses or having several kids from karate class for a sleepover.

* ''WesternAnimation/StevenUniverse'': Steven has a VagueAge for the first season and a half, but in "Steven's Birthday" is revealed to be turning fourteen. His MuggleBestFriend and LoveInterest, who's not even thirteen but is more mature, is shocked. Aside from the fact that he still sleeps with a teddy bear and generally acts like he's under eleven, Steven also [[OlderThanHeLooks looks quite younger]]: because [[HalfHumanHybrid his mother]] was [[TheAgeless an ageless alien]] whose species have their physical forms match their mental ages, this ended up applying to Steven as well, with his dad showing Connie a scrapbook showing that Steven hasn't physically aged since he was eight. ''[[WesternAnimation/StevenUniverseFuture Future]]'' would finally have a more mature (but emotional unstable) Steven who finally looks his age (at that point, 16).

* ''WesternAnimation/MaxAndRuby': Max starts out at 3 and speaks in one word sentences. As a 4-year-old he speaks in complete sentences but not in fluent English. He is the only kid in his class unable to do so.