'What Happens In Vegas' (PG-13)' (out of four)

You would almost think that you've seen Cameron Diaz and Ashton Kutcher paired up before the new movie "What Happens In Vegas." They seem such a likely duo of goofballs that it's amazing no one ever dreamt up that casting coup before.

While the script is as predictable as a cheap steak buffet in Sin City, the two make it all worthwhile. After being dumped by her stuck-up boyfriend (Jason Sudeikis), Joy (Diaz) and her bartender friend Tipper (Lake Bell) take off to Las Vegas. Meanwhile, Jack (Kutcher) and best friend Hater (Rob Corddry) have the same idea when Jack gets fired from his furniture-making job by his boss, who also happens to be his father (Treat Williams).

The pair accidentally meets in Las Vegas when a room mix-up lands them in the same suite. After convincing the front desk clerk to give them each a penthouse suite (does that happen?) and then a fistful of free comps (does that happen?), the pair with best pals in tow take off on a night of true Vegas Strip debauchery (yes, that does happen). They wake up to find they've slept together and married each other -- but the quickie run down the aisle leads to even more trouble when Jack drops a quarter owned by Joy into a quarter slot machine and wins $3 million (does that really happen?).

To get the marriage dissolved and decide who gets the fortune, the two visit a New York judge named Whopper (Dennis Miller), but rather then grant the separation, he forces them to spend six months trying to make the marriage work.

Joy is sentenced to move into Jack's disheveled bachelor pad, complete with single-guy disgusting bathroom. "Were you training monkeys in here?" Joy asks.

The typical jokes of man vs. woman living arrangements, including her taking too long in the bathroom and he leaving the toilet seat up, get stale after a while, but the battle between two of the prettiest people on Earth is laugh-out-loud funny. Diaz and Kutcher look like they couldn't have had more fun making each other miserable.

At one point, moviegoers will be forced to wonder if the knock-down sparring is actually too real. Are the actors trying to outdo each other to claim top spot as the star of the two-person film? Diaz gets top billing in the credits, however.

Nonetheless, "What Happens In Vegas" gambles on the star appear of its two leads -- and the payoff is pure fun.