Foster's Home for Imaginary Friends - Season 3 (2005)

Someone named Goofball John McGee stumbles onto the Foster's property. Frankie thinks he's not really an imaginary friend, just a fraud; really a teenage kid in disguise, but everyone else believes otherwise. He always needs help with stuff, always at Frankie's expense. She is even more infuriated when they refuse to believe her when they think he really is an imaginary friend. So Frankie is more than anxious to expose him as a fake.

Duchess gets adopted by Mac's neighbors, but her constant loud complaining becomes too much for Mac's mother to handle. Terrence tells Mac that they're moving, and Mac tries to get his neighbors to get rid of Duchess. When this fails, he tries to bring her back to Foster's. Terrence warns everyone at the house, and they try to prevent her from getting back in.

Mac wins tickets for a trip to Europe, but everyone causes delays while packing. Already late for the trip, Frankie tries to make sure that Madame Foster can handle taking care of the house while she's gone, but Madame Foster just wants to break the rules.

Mac meets a girl named Goo who begins to follow him to Foster's every day. Her over-active imagination creates many new imaginary friends, which causes Foster's to become overcrowded.

Mr. Herriman's addiction to carrots causes him to hide carrots around the house. With no carrots, the only thing to have for dinner is a dish simply called "It." Mr. Herriman begins to punish anyone who comes near his hidden carrots, and Bloo tries to get in trouble so he doesn't have to eat "It."

Eduardo gets fleas, with whom he becomes close friends, much to the consternation of Frankie and Mr. Herriman. Bloo, on the other hand, wants some fleas of his own.

When several imaginary Santa Clauses are brought to Foster's, Mac begins to doubt that Santa is real. Bloo and the other friends try to prove to Mac that he exists. Bloo also tries to get Mr. Herriman to hand out more that one present to each person.

Mac creates a film about Foster's for a school project, but Bloo edits and it changes it into something completely different. Eventually, the film gets entered in a film festival.

Tired of Mr. Herriman's rules, Frankie and Bloo run for president of Foster's. When Bloo loses, he spreads untrue facts about Frankie to everyone in the house.

A newly-adopted friend leaves a room vacant and Bloo, Wilt, Eduardo and Coco all compete for it, as does another imaginary friend named Peanut Butter.

Coco lays eggs containing imaginary friend trading cards, and Bloo tries to be the first to collect all of them.