After his girlfriend Tracy breaks up with him, Erik Stifler and his friend Mike “Cooze” Coozeman arrive at the University of Michigan as freshmen. On arriving at his dorm, Erik meets a girl named Ashley while she is taking a shower in the coed bathrooms. He then meets his new roommate Bobby and his girlfriend Margie while they are having sex. Erik is then welcomed by his cousin, Dwight Stifler, the leader of the Beta House fraternity, who invites Erik, Cooze, and Bobby to a Beta House party. They meet Wesley, the rush chair of Beta House who experiences blackouts after drinking alcohol, and learn how they can gain eligibility to pledge for the Beta House. They are also informed by Dwight that the Geek House, formed by wealthy nerds, has been trying to shut down Beta House.
Erik and Ashley begin dating, but on their first date at a restaurant, Erik has hot soup spilled accidentally on his legs, so Ashley brings him to her room to clean up. As Ashley rubs lotion on Erik’s thigh, he develops an involuntary erection and accidentally ejaculates over her possessions. Erik apologizes and explains to Ashley that, after breaking up with Tracy, he has not ejaculated in four months, masturbation being a taboo in his house because of a previous incident. Meanwhile, Cooze falls in love with Ashley’s roommate Denise; however, she is nervous about showing her genitalia and having sex with him, so she gives Cooze a handjob instead. After talking with Erik, Bobby, and Dwight about Denise, Cooze develops suspicions that Denise might have a penis, so Dwight encourages him to find out.
Along with two other pledges, Erik, Cooze, and Bobby complete fifty tasks to pledge the Beta House, including: getting their posteriors signed by a stripper, having sex with a professor, marrying a fellow pledge in Canada, and placing a live ostrich in the Geek House. While completing these tasks the Beta House members are banned from the Silver Dollar, their favorite strip club and bar, after the Geek House buys the locale. After they complete their final task (stealing something from the Geek House), Edgar, the president of the Geek House, challenges the Beta House to the Greek Olympiad, with the winners taking the loser’s House. Before the competition starts, Dwight learns from Rock that while attempting to join the midget fraternity, Edgar had sex with a sheep previously.