After his (pretty tame) bachelor party, Paul (Jason Lee) wakes up with Becky (Julia Stiles), a tiki dancer, and tries to hide the indiscretion from his fiancée, Karen (Selma Blair) -- a decision that leads to the inevitable comedy of compounding cover-ups. It's not even that simple: Karen is the daughter of Paul's boss, Becky turns out to be Karen's cousin and further has a jealous ex-boyfriend who's a sadistic cop (Lochlyn Munro), and Paul's brother (Thomas Lennon) secretly covets Karen. Directed by local guy Chris Koch, the movie aims for witty, warm moments yet often (and unnecessarily) succumbs to scatological humor. The result is not-so-screwy mayhem and marginalized romantic chemistry. Lee is passable as the lightning rod, and so is Blair as the perky trophy-wife-to-be, but the film belongs to Stiles: her goofy sass makes this "guy thing" her own. (98 minutes) At the Entertainment, Flagship, Holiday, Providence Place Mall 16, Showcase, and Tri-Boro cinemas.