Monkey’s birthday party is interrupted by Barbequor (Robert Ridgely), an intergalactic villain who plans to eat the planets, and his sidekick, the Silver Spooner (Rob Paulsen).
Dexter is disappointed when he ends up at an Amish farm instead of a high-tech farm for summer camp. His attempts to modernize the Amish family do not go well.
Banned from watching a late-night movie due to his young age, Dexter uses his technology to artificially grow into adulthood, but Dee Dee tampers with his machine, causing Dexter to turn into an old man.
In a fit of rage, Dexter dumps Dee Dee’s favorite teddy bear into the garbage. An upset Dee Dee begins to behave oddly, prompting Dexter to go to the garbage dump and get it back.
Dexter’s father is challenged to an arm wrestling match by a man named Earl at a truck stop. Stunned at the strength of Earl and his determination to beat his father, Dexter attaches a robotic arm to his father to enable him to win.
Dexter’s new device allows him to study for the next day’s French test while sleeping. It malfunctions, causing a single phrase (omelette du fromage) to repeat throughout the night, causing Dexter to wake up the next morning speaking nothing else except omelette du fromage.
When Dexter is bitten by a clown’s dentures, he begins turning into a mad clown every night, terrorizing the town with his mayhem, and only Dee Dee, who knows mime, can stop him.
In need of an assistant to operate his latest invention, Dexter performs a brain transplant on Dee Dee to make her smart enough to fulfill the role. With her new brain, Dee Dee proves to be more intelligent than Dexter.