Starring Cameron Diaz and Ashton Kutcher. Rated PG. Opening Friday, May 9, at the Cinemark Tinseltown

What Happens in Vegas… doesn’t actually stay in Vegas. Although the bland direction of Tom Vaughan makes only cursory use of exterior locations, most of the action takes place in New York. That’s where newlyweds Joy (Cameron Diaz) and Jack (Ashton Kutcher) return to sober up after a weekend of drunken debauchery leads to the kind of white-trash wedding ceremony that would make Britney Spears blush.

From there, it’s the battle of the doe-eyed cuties. Despite the fact that Jack and Joy look perfect enough to share the same exhausting skin-care regimen, Dana Fox’s script attempts to make the most of their clashing personalities. Joy is a strait-laced stockbroker who plans her life down to the last detail. Jack is a charming slob who can’t hold down a job. It’s a bit like watching The Odd Couple being played out by a pair of hot-looking underwear models.

The twist? Jack has won $3 million on a Vegas slot machine using Joy’s quarter. When they go to court to sort things out, their antics annoy a crusty, family-values-type judge (Dennis Miller). He reserves a decision on awarding the money, forcing the young couple to live together and go to a therapist (Queen Latifah). Although there are a few genuinely funny moments—including a scene in which Joy lectures Jack on toilet-bowl etiquette as if she’s training an especially dumb dog—Kutcher and Diaz never really mesh as a believably romantic couple.

Nobody could ever accuse Diaz of being a great actor, but she gamely delivers what we’ve come to expect. It’s Kutcher who inevitably messes up. He’s alarmingly wooden whenever he strays out of his limited goofball shtick, leaving plenty of room for The Daily Show’s Rob Corddry to steal the show as Jack’s dopey best friend.