The episode begins at the bus stop with Mikey and his mother, Mrs. Blumberg, who embarrasses her son by treating him like a child and reminds him of his 10th birthday on Saturday and that from Monday he gets to wait at the bus stop all by himself, as the bus leaves for Third Street School.
However, when Mikey does arrive, he appears to be mesmerized, staring at the kindergartners for a brief moment until Spinelli calls for his attention. However, as recess ends, one of the kindergartners drops their sippy cup, which features the children's character Bonky the Green Dragon, and immediately brings back memories of Mikey's childhood.
The next day, Mikey just walks past his friends, and The Gang immediately notice something is up with him. True to their word, Mikey is struggling to adapt to his new status as a 10-year-old, and has brought a Bonky doll to school, also uttering "George Bonkyton" in class which prompts an outbreak of laughter. Mikey has regressed to a kindergarten-like state, and Bonky is once again dominating his life.
At Mikey's 10th birthday party, the Gang is horrified to find that the party is Bonky-themed, with a Bonky pinata, a Bonky cake, "Pin the Tail on the Bonky", and to add salt to wound, none other than Bonky himself appears, and Mikey and the kindergartners dance with the figure. The gang has no other choice but to confront Bonky and they knock him over. When they unmask the mascot, it is revealed to be Mrs. Blumberg in a costume, traumatizing Mikey.
Outside, Mrs. Blumberg finds her son sitting in the backyard. She apologizes to him, and realizes Mikey is a bit too old for Bonky, telling him she'll always be with him in his heart. At the bus stop the next day, Mikey leaves for school, for the first time on his own, thanks to the help of Mrs. Blumberg.
- Before "The Girl Was Trouble"
- Coloring error: When the gang arrive at school the next day after Mikey re-discovers Bonky, T.J.'s pants are tan.
- Animation error: When T.J. is explaining to the gang what to do about Mikey's Bonky obsession, one of his freckles disappears for a frame.
- Coloring error: When the gang are at the bike racks the next day, Gretchen's helmet is blue. After Vince notices that Mikey doesn't care about turning ten, her helmet is red.
- Animation/coloring error: When Miss Grotke asks the class a question about George Washington, Ashley Q.'s jacket is white, and Megan's sweater is missing. In the next shot of the class, Megan has black hair and dark skin, the stripes on Lily's shirt are missing, and the stripes on Gordy's shirt are missing.
- Coloring/animation error: When Mikey answers, "George Bonkyton", the front of Willy's hat is white, and Gordy's shirt has long sleeves.
- Coloring error: When Miss Grotke tells Mikey that he did a good save, the top part of the stripe down her dress is light green.
- Coloring error: When Mikey is walking before he gets hit with a kickball, his backpack is green. When the Bonky merchandise inside is dumped out, it's red.
- Coloring error: When Mikey holds up his Bonky puppet in the lunch line, it's colored a more mint green than light green.
- Animation error: When the gang arrive at Mikey's door for his party, the tie Gus was wearing is missing.
- Animation error: When Gus points out that "Bonky" is at Mikey's party, Gretchen is drawn with her usual hair beads instead of her bows.
- Error: When Mikey and his mom are talking, Gretchen says that she read their lips, yet they are facing away from the window.
- During the party, Mikey was wearing his Bonky shirt, but in one frame when he and his mom were talking, he was wearing his normal shirt.
- This was the final episode before the movies to be colored with digital ink and paint.
- Bonky is a parody of the popular children's character, Barney the Dinosaur.
- This episode was cut from the Italian dub.
- This episode was paired up with "The Dude" outside the US.
- On BSkyB's electronic programming guide, it listed the episode summary as "Gus has to part with his favorite childhood toy". This is incorrect, as the episode is about Mikey, not Gus.
- This was the final episode with animation by Toon City.
- This is the third episode where a character celebrates their birthday, the first being "The Girl Was Trouble" for Gretchen's birthday (Though her birthday took place a week prior to the events of the episode), and the second being "Randall's Friends", for Randall's birthday.
- This is the final episode where Mikey's parents have speaking roles.
- This is the fourth episode where T.J. wears his "formal" wear; he previously wore it in "The Experiment", "One Stayed Clean", and "The Biggest Trouble Ever".
- This is the third episode where Spinelli wears her first "formal" outfit; she previously wore it in "The Experiment" and "The Biggest Trouble Ever".
- This is the third episode where Vince wears his first "formal" outfit; he previously wore it in "Teachers Lounge" and "The Biggest Trouble Ever".
- This is the second episode where Gretchen wears her second "formal" outfit; she previously wore it in "The Biggest Trouble Ever".
- This is the second episode where Gus is shown wearing a tie with his outfit; the first being "The Biggest Trouble Ever".
- T.J. Detweiler - Andrew Lawrence
- Vince LaSalle - Rickey D'Shon Collins
- Ashley Spinelli - Pamela Adlon
- Gretchen Grundler - Ashley Johnson
- Mikey Blumberg - Jason Davis
- Gus Griswald - Courtland Mead
- Ms. Finster/Mikey's Mom - April Winchell
- Miss Grotke - Allyce Beasley
- Ashley Armbruster/Bonky Theme Singer #1 - Anndi McAfee
- Ashley Boulet/Bonky Theme Singer #2 - Francesca Smith
- Lunchlady Irma - Tress MacNeille
- Mikey's Dad - Sam McMurray
- Kid #1 - Ryan O'Donohue