In the small town of East Great Falls, Michigan, high-schooler Rob Bug Hall finds himself caught in an awkward situation right from the start. He is caught on camera masturbating with a peanut butter sandwich by his dog, while his younger brother, Cody, films the entire incident and later uploads it to YouTube, leading to embarrassment and chaos for Rob. This incident sets the tone for a rebellious and humorous exploration of teenage life centered around sex, friendship, and self-discovery.
At school, Rob quickly bonds with his fellow virgin friends Nathan and Marshall "Lube". During their conversations, Nathan reveals that his girlfriend, Dana, has promised to remain abstinent until marriage—even though she has already "broken" that pledge by sleeping with several others. Tension heightens when Rob's crush, Heidi, is threatened by Scott Stifler, who aims to make a move on her, sparking a rivalry that adds a layer of competition and humor to the story.
Meanwhile, Lube daydreams about the alluring cheerleader Ashley, fantasizing about the possibility of hooking up with her. Rob and Heidi meet in the library, where she confesses her burning desire to lose her virginity as soon as possible, setting the stage for their tentative relationship. Their budding romance is soon tested during the school's dance, where Nathan's awkward attempt at intimacy with Dana leads to an embarrassing fallout when he expects sex after performing oral on her in his car. Rob, wanting to express his feelings, tries to confess to Heidi but is interrupted by the chaos surrounding Nathan and Lube.
The situation escalates when Rob finds Heidi in the library, about to have sex with someone else. Shocked and overwhelmed, he accidentally drops a lit tiki torch, igniting a fire and triggering the sprinkler system, which halts the moment and causes chaos. The next day, while cleaning the library for detention, Rob discovers a damaged copy of "The Bible," a legendary sex manual compiled by students over four decades. Inspired by a tip in the book, Rob approaches Ashley in a lingerie store, where she boldly shows her breasts and encourages him to shoplift panties for her. Rob gets caught and must pay for them with his mother’s credit card, leading to an awkward confrontation at home.
Things take a turn for the worse when Nathan's attempt at a romantic gesture at Dana's church backfires spectacularly. Nathan accidentally broadcasts their private conversation over the church’s PA system, leading to embarrassment and Dana’s father forbidding her from seeing him. Meanwhile, Rob’s mother confronts him about the credit card purchase, and the embarrassing footage of Rob wearing women's underwear gets posted online again, amplifying his reputation as the school’s laughingstock.
Rob's confidence continues to wane, especially when he fails to muster the courage to confess his feelings to Heidi at a basketball game. Following a misadventure inspired by "The Bible," Rob and his friends visit a Canadian prostitute, only to be horrified when they meet Monique, the elderly sex worker, who unwittingly dies during the encounter. Panicked, the boys hurriedly leave, feeling more humiliated and confused about their sexual journeys.
Finally, Rob gathers enough courage to tell Heidi how he feels, and she responds positively, agreeing to meet him at Stifler’s party. At the party, Heidi overhears Rob exclaiming, “Tonight, I’m getting laid!” which causes some tension. Lube tries to win over Ashley but is turned down after a misunderstanding and finding an offensive text. Nathan’s attempts to make amends with Dana are also unsuccessful, leading to more misunderstandings.
The night takes a downward spiral when Rob discovers Heidi in bed with Stifler. Overcome with disappointment and alcohol, Rob rudely declares that “only assholes get laid,” and in his drunken state, he drunkenly tries to seduce a girl but vomits on her before anything happens. The following morning, Rob’s mother shows him a video of his drunken antics, adding to his shame.
Resolving to set things right, Rob and his friends embark on a mission to find the original contributors of the damaged Bible, eventually successfully recreating the missing pages. During a ski trip, Katie, who was upset over losing her virginity to Stifler, defeats him at strip poker and forces him outside naked—where he is hilariously sodomized by a moose. This bizarre yet comedic event leads to Stifler bonding with Imogen. Meanwhile, Nathan’s attempt at passion with Dana ends with an accidental power shutoff, trapping Rob and Heidi on the ski lifts. In that moment, they reconcile, share a kiss, and all seems to be right again.
Back at the cabin, Rob and Heidi finally have sex, and Lube and Ashley follow suit, sealing their relationships. The story concludes with Rob returning the fully restored Bible to the library, signing his name in it, symbolizing his growth and newfound confidence. Meanwhile, Cody stumbles upon a viral online video of himself with a vacuum cleaner on his penis—something that has been viewed nearly 10 million times—highlighting the absurdity and unpredictability of teenage life. The film ends with Rob appearing in the viral video, crafting a humorous and rebellious endnote to their adolescent escapades.
