Dee Dee enters the land of her imaginary friend Koosalagoopagoop.

When Dexter learns that Dee Dee is trying to make a science project alone, he decides to help her, but she does not want his help.

Mandark disguises himself as Dexter’s mom to get into Dexter’s Lab. Unfortunately for Mandark, he now has to deal with Dexter, Dad, and Dee Dee’s requests, which are too much for him.

Dexter’s mother attempts to support him during a chess tournament but does nothing but embarrass him.

Dexter tries to avoid being pushed into the family’s new swimming pool by his father, since he cannot swim and is afraid of water.

Intergalactic wrestling champion Rasslor (“Macho Man” Randy Savage) challenges Earth’s superheroes, including Monkey, with the planet’s fate at stake.

Mandark’s birth and origins as the child of hippies are revealed, as is the beginning of his rivalry with Dexter and the cause of his villainy.

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.

Dexter and Dee Dee experiment with coffee after seeing how it energizes their parents in the morning.

When Dexter discovers that Beau, Dee Dee’s new boyfriend, has similar interests as him, Dexter tries to steal Beau’s attention from Dee Dee.

Peltra wants to turn Monkey into a fur coat.

Dee Dee learns a new game that can predict the future events.

Dexter pirates cable for his father.

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.

When Dexter cannot get the ice cream truck to stop for him, he creates a series of obstacles to do so.

Dexter creates a device to make a lifelike superhero comic, with his sister villain “Deestructa”.

A nature documentary team observes “Blackfoot” (Dexter) and “Slim” (Dee Dee) in their “natural habitat”.

To learn more about girls, Dexter camouflages himself and enters Dee Dee’s room, where she is having a sleepover with her friends Lee Lee and Mee Mee. He gets caught by the girls, who force him to take part in their activities.

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.

Quackor returns to battle Monkey in Dexter’s Lab until Quackor lays an egg; then the two fall in love.

Valhallen loses his magic ax and starts turning into a nerd, forcing Major Glory and Krunk to enter his room to find it.

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 and Dee Dee compete against each other on a game show.

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