Darren Silverman (JASON BIGGS) and his buddies Wayne (STEVE ZAHN) and J.D. (JACK BLACK) have been best friends for years and even have a band, Diamonds in the Rough, named after their musical idol, Neil Diamond. Since Wayne, a pest control wrangler and J.D., a fired Subway employee, know that Darren, a social worker, has never gotten over Sandy (AMANDA DETMER), the girl of his dreams from school, they decide to fix him up with someone else.
Their latest target is Judith (AMANDA PEET), a pretty but vexed psychologist they spot in a bar. Although Judith initially wants nothing to do with Darren, the two hit it off and become romantically involved. Once around the demanding and unfriendly new girlfriend for several weeks, however, Wayne and J.D. decide she's not the right woman for him, particularly after she tells Darren that he must quit the band and never see his friends again.
Unfortunately, Judith has already proposed to him and Darren seems unable to see what sort of woman she really is. As such, Wayne and J.D. then set out to do what they can to break up the relationship, including kidnapping Judith, reintroducing Darren to Sandy who's about to become a nun, and enlisting the aid of their former football coach (R. LEE ERMEY) and even Neil Diamond (NEIL DIAMOND) himself in their scheme.