After leaving the prison, the dwarf criminal Calvin Sims joins to his moron brother Percy to steal an expensive huge diamond in a jewelry for the mobster Walken. They are chased by the police, and Calvin hides the stone in the purse of the executive Vanessa Edwards, whose husband Darryl Edwards wants to have a baby. Percy convinces Calvin to dress like a baby and be left in front of the Edwards's house to get inside the house and retrieve the diamond. Darryl and Vanessa keep Calvin for the weekend and decide to adopt him, while Walken threatens Darryl to get the stone back.

The story begins with a regular Joe who tries desperately to seek employment, but embarks on a violent rampage when he teams up with cult leader Uncle Dave. Their first act is to heist an amusement park, only to learn that the Taliban are planning the same heist as well. Chaos ensues, and now the Postal Dude must not only take on terrorists but political figures as well.

The movie will shift its focus on Erik Stifler, the cousin of Matt and Steve, a youngster who is nothing like his wild relations. Peer pressure starts to turn him to live up to the legacy of the other Stiflers when he attends the Naked Mile, a naked run across the college campus. Things get worse when he finds that his cousin Dwight is the life of the party down at the campus.

A circus' beautiful trapeze artist agrees to marry the leader of side-show performers, but his deformed friends discover she is only marrying him for his inheritance.