After his girlfriend Tracy breaks up with him, Erik Stifler and his friend Cooze arrive at the University of Michigan as freshmen. Erik meets a girl named Ashley and his new roommate Bobby. Erik is then welcomed by his cousin, Dwight Stifler, the leader of the Beta House fraternity; who invites Erik, Cooze, and Bobby to a party. They meet Wesley, the rush chair of Beta House who experiences alcohol blackouts, and learn how they can gain eligibility to pledge for the Beta House. They are also informed by Dwight that the Geek House, ran by wealthy nerds, has been trying to shut down Beta House.
Erik and Ashley go on a first date at a restaurant where 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 accidentally ejaculates on her belongings. Erik apologizes and explains to Ashley that, after breaking up with Tracy, he has not had an orgasm in four months due to 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 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.
Along with two other pledges, Erik, Cooze, and Bobby complete fifty tasks to pledge the Beta House, including: getting their butts signed by a stripper, having sex with a professor, marrying a fellow pledge, and placing a live ostrich in the Geek House. 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 that while attempting to rush the midget fraternity, Edgar had sex with a sheep.
Being the Olympiad's last winner, Beta House alumnus Noah Levenstein returns to campus to officiate the competition. The first game is won by Beta House as Dwight and Edgar compete in removing girls' brassieres. Geek House win the next three matches: a pugil bout turned lightsaber duel, catching a greased pig, and a two-person "69" race. Beta House wins the fifth and sixth competitions: a Russian roulette challenge between Dwight and Edgar with aged horse semen; and a beer drinking competition between all members of both Houses ultimately won by Wesley via a keg stand.
During the final lap dance challenge, Beta House uses Edgar's sheep fetish against him with Bobby's girlfriend Margie wearing a sheep costume, resulting in the Geek House losing the Olympiad. Having won the Geek House mansion, the Beta House hosts a toga party. Erik and Ashley establish their relationship and have sex. Meanwhile, Cooze and Denise finally sleep together as well, and Cooze discovers that what Denise is hiding is the fact that she ejaculates during sex, much to his excitement. In a post-credits scene, Edgar instructs a stripper at the Silver Dollar to dance with the headpiece of the sheep costume.
John White as Erik Stifler
Steve Talley as Dwight Stifler
Jake Siegel as Mike "Cooze" Coozeman
Nick Nicotera as Bobby
Meghan Heffern as Ashley Thomas
Tyrone Savage as Edgar Willis
Sarah Power as Denise
Eugene Levy as Noah Levenstein
Christopher McDonald as Mr. Stifler
Angela Besharah as Irene
Jonathan Keltz as Wesley
Dan Petronijevic as Bull
Christine Barger as Margie
Bradford Anderson as Jake Parker
Robbie Amell as Nick Anderson
Italia Ricci as Laura Johnson
Rachel Skarsten as Sharon
the third installment in American Pie Presents film series
a spin-off of the American Pie franchise
sequel to 2006's The Naked Mile