"TJ gone. I Big Kid now!"
TJ gets captured by the kindergartners, but as his friends search for him, he gradually becomes one of them.
Tropes:
- Big "NO!": Vince when Gretchen finds TJ's shoe.
- Bittersweet Ending: The kindergartners let TJ and his friends go after he remembers he is a fourth-grader, but Gretchen tells him holding onto that nostalgia isn't healthy. Everyone has to grow up, even the kindergartners.
- Broken Tears: TJ when he realizes that he is a fourth-grader.
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Chaotic Neutral: It's revealed that the kindergartners aren't fundamentally evil. They're meant to represent how free kids are before they enter the first grade and start learning for real. When TJ leaves them, Captain Sticky gives him a look of sorrow before releasing him. - Chekhov's Gun: TJ's Kirby Pucket baseball card is used by his friends to bring TJ back to a fourth-grade mentality.
- Going Native: TJ reverts to kindergarten mentality the longer he spends with the kindergarteners since they refuse to release him and the only way to get along is to play with them.
- Growing Up Sucks: The crux of the episode is that TJ's friends have to remind him that he can't go back to the kindergartner's lifestyle and that the kindergartners themselves will graduate into the first grade (a fate that befalls Hector and Tubby at least by Taking the Fifth Grade).
- Kiddie Kid: TJ briefly acquires the mindset of a five-year-old towards the end of the episode. TJ is nine.
- Noble Savage: This is one of the episodes wherein the kindergartners are portrayed sympathetically. TJ even enjoys the pleasures of fingerpainting and naptime.
