Plot
Home for the summer after college, Jim Levenstein, Kevin Myers, Chris "Oz" Ostreicher, and Paul Finch attend Steve Stifler's party until the police shut it down. Kevin is inspired by his brother to rent a Lake Michigan beach house and throw a massive party to close out the summer.
The guys obtain jobs painting houses to afford the rent. Jim receives a call from former love interest Nadia who informs him that she plans to visit. To gain sexual experience, Jim seeks out his prom date Michelle, who agrees to help him after he is mistaken for a mentally disabled trombone prodigy and makes a fool of himself in front of a band camp concert audience.
The group hosts a small party where Kevin and his ex-girlfriend Vicky awkwardly lie to one another regarding the number of sexual partners they have had at college. Oz attempts to have phone sex with his girlfriend Heather while she is studying abroad in Spain but they are interrupted by Stifler.
While painting a house, the guys observe the two female occupants Stifler assumes are lesbians and he enters their home while they are away to find proof. Jim and Finch pursue him inside in an attempt to stop him when the women return home and find the trio inside. They tempt the boys with some quid pro quo sex acts. However, when Stifler exposes his genitals after the women request watching the boys give each other handjobs, Finch and Jim leave in disgust.
Jim visits Michelle again to obtain sexual tips and they are nearly caught by a camp director. Stifler brings the group pornography and Jim later accidentally picks up super glue instead of lubricant. After hospital treatment, he learns his penis will be "unusable" for a short period of time. Meanwhile, Finch has become involved in the art of Tantra and waits to use his new skills with Stifler's mom, whom he mistakenly believes has arrived and is disappointed when he learns it is Stifler's younger brother.
Nadia unexpectedly arrives early, much to the dismay of Jim as his penis has not fully healed. Michelle agrees to pretend to be in a relationship and will later break up. However, she comes to realize that she has fallen for him, but stages a mock breakup the night of the party so that Jim is free to hook up with Nadia. As the party begins, Jim realizes that he loves Michelle, so he lets a disappointed Nadia down gently. Jim rushes to the band camp and interrupts Michelle's concert performance to kiss her onstage, after which they return to the party together.
Meanwhile, Sherman is seduced by Nadia who is attracted to his geeky persona. Kevin is disappointed to learn Vicky has brought a date so he storms off onto the beach. Oz is happy when Heather unexpectedly arrives early. Jim, Oz, and Finch speak to Kevin, who admits he is struggling to move on after high school, but they reassure him and convince him to return to the party.
When the group returns, Kevin apologizes to Vicky, and they all enjoy an evening of partying together. The two "lesbians" arrive to the party and later have a threesome with Stifler.
The next day, the guys are preparing to leave when a car pulls up; Finch approaches and finds it is Stifler's mom. They drive off together and have sex in the car.
