A garbage can spaceship is seen flying near Earth. The same garbage can is then shown inside an antique shop owned by Captain Manzini (Anthony Newley).
A boy named Dodger(Mackenzie Astin) is being assaulted by four older teenage bullies in a park. Juice (Ron MacLachlan), the leader, steals Dodger’s money and drops him in a puddle.
Dodger goes to Manzini’s antique shop where he works. Manzini takes Dodger’s clothes and cleans them while warning him to stay away from the garbage can.
Later, Dodger sees Tangerine (Katie Barberi), Juice’s girlfriend, who seems to be the most compassionate one towards Dodger, and tries to persuade her to buy something. Dodger is attracted to Tangerine and covertly smells her hair while she is distracted. The other bullies enter the shop and attempt to rough up Dodger again, but he manages to outwit them. However, amidst the tussle, the garbage can is knocked over. The bullies then bring Dodger into a sewer, handcuff him to a rail, and open a sewage pipe on him. Dodger is saved by little mysterious people named the Garbage Pail Kids.
Manzini returns and is upset that the Garbage Pail Kids have been released from their can, but introduces Dodger to each of them: Greaser Greg is a leather jacket-clad greaser with a violent attitude; Messy Tessie is a girl with a constantly runny nose; Windy Winston is an insane boy who wears a Hawaiian shirt and often farts violently; Valerie Vomit is a girl who throws up on command; Foul Phil is a whining hungry baby with halitosis who constantly asks characters if they are his “mommy” or “daddy”; Nat Nerd is an obese acne-riddled boy who poorly dresses up like a superhero and wets his pants frequently; and Ali Gator, the group’s natural leader, is an anthropomorphic half person/half alligator who has an appetite for human toes. Manzini explains that the kids are forbidden from going in public, because they’ll be attacked by the “normies” (normal people), and that he can’t get the kids to go back into the garbage can without magic…