When Dexter gets amnesia, Dee Dee decides to play tricks on him by creating a whole new identity for him in her image.

Dexter’s life story, from his birth to the creation of his secret laboratory, is retold as an opera.

Dexter’s parents discover that he is making false excuses to get out of physical education and now Dexter must pass a physical exam if he wants to pass P.E. and move up a few grades.

Monkey encounters Simion (Maurice LaMarche), an intelligent anthropomorphic chimpanzee who seeks vengeance on humans for turning him into his current state.

Dexter and Dee Dee’s secret decoder rings hold the keys to joining the Action Hanks and Pony Puff fan clubs respectively, but they interchange the clues by mistake, causing them to switch clubs.

When Dee Dee claims that anything can be hers because Dexter “doesn’t have his name on it”, he invents a label-making gun.

While out for dinner at a pizza restaurant, Dexter tries to slow down the “Whack the Weasel” machine to win a stuffed Monkey doll before Dee Dee does. Security captures him for tampering with the machine, and he falls into the hands of a mad scientist.

Due to overworking his brain, Dexter’s mind shuts down, making him act idiotic.

Dee Dee wins a golden diskette, earning her a free trip to the laboratory of Professor Hawk (Tom Kenny), one of Dexter’s favorite scientists.

Again tired of being short, but mindful of his past failures, Dexter decides to make everyone shorter than himself.

Dexter tries to make himself and Dee Dee older to see an R-rated movie, but he accidentally makes everybody else babies instead.

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 Dee Dee causes Dexter to mistakenly take a book from the library without checking it out, they sneak into the library at night to put it back.

Dee Dee accidentally shuts down Dexter’s lab, and he has to power it back. In the process, Dee Dee attempts to keep Dexter from finding out what she really did.

Dexter and Dee Dee refuse to flush their dead goldfish into the toilet and are later haunted by its spirit.

Dexter refuses to admit that blondes have more fun, so Dee Dee secretly dyes his hair blond to prove it to him.

Old Dexter And Old Dee Dee’s talks about the glory days, and his sister is still there to inject her opinions, telling him what really happened.

Dexter’s father is left to watch the kids while his wife visits her sister.

Dexter tries to turn himself into a superhero, but gives up after every power he tries backfires.

While on a date with Agent Honeydew, Monkey gets hypnotized by the music of the Organ Grindor (Jim Cummings), who commands him to rob Fort Knox.

Dexter’s father sleepwalks into Dexter’s lab. Dexter discovers this, and now has to escort him out of the lab without waking him up, which proves more difficult than thought.

Dee Dee and her friends, Lee Lee and Mee Mee, enter Dexter’s lab and wreak havoc. Dexter clones himself to stop them, but the girls too make clones of themselves.

When Dexter uses anti-matter on the family car to shorten road trips, he accidentally fuses Dee Dee with the car.

When Dexter cannot reach anything in his lab, he makes himself more flexible by combining himself with bubble gum.