It's a week before the big wedding day and Paul (JASON LEE), an ad salesman who works for his future father-in-law, Ken (JAMES BROLIN), is set for his bachelor party thrown by his older brother, Pete (THOMAS LENNON), and best friend, Jim (SHAWN HATOSY).
Among the "entertainment" for the evening are three hula girls - including Becky (JULIA STILES) who's on her first day working the job. She's not very good, but she hits it off with the somewhat drunken Paul, unaware that he's the groom-to-be.
The next morning, a phone call from future mother-in-law Sandra (DIANA SCARWID) awakens Paul and he discovers Becky in his head. Unable to remember what happened between them, he hurries Becky out the door before his fiancée, Karen (SELMA BLAIR), arrives. His neighbor, Minister Ferris (LARRY MILLER), is not amused.
Discovering Becky's underwear just as Karen arrives, he races to hide it and sets off on a course of progressive lies to cover up what may or may have happened with Becky. Things get more complicated at a dinner hosted by Karen's parents. Not only are his mom, Dorothy (JULIE HAGERTY), and stepfather, Buck (DAVID KOECHNER), in attendance, but so is Karen's Aunt Budge (JACKIE BURROUGHS) and cousin, who turns out to be none other than Becky.
Unable to avoid eventually "meeting" her, Paul scrambles to make up more lies, some of which are covered by other men since "it's a guy thing" to do. The situation worsens, however, when Becky's jealous and deranged ex-boyfriend cop, Ray (LOCHLYN MUNRO), shows up and is none too happy about photos taken of her and Paul. As the big day approaches, Paul does what he can to cover his various lies and prevent Karen from learning about what happened.