Extremely shy Lars finds it impossible to make friends or socialize. His brother and sister-in-law worry about him, so when he announces that he has a girlfriend he met on the Internet, they are overjoyed. But Lars’ new lady is a life-size plastic woman. On the advice of a doctor, his family and the rest of the community go along with his delusion.

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