Don't fret about laughs staying in Vegas with Diaz and Kutcher

Since a successful adventure-movie franchise can clearly be built on an amusement park ride, then why not make one measly romantic comedy based on a civic slogan? And why not make it with, I don't know, James van der Beek and Demi Moore? No, wait! Ashton Kutcher and Cameron Diaz!

There are, it turns out, a few reasons why not. For one, the time that an Ashton Kutcher/Cameron Diaz pairing like this would have hit the target market bull's eye can be roughly traced to about the late Furby Era. For another, the battle of the sexes humor "What Happens in Vegas" trades in -- he leaves the seat up! She has credit cards! -- is about as hot as the aforementioned Mr. van der Beek's movie career.

But whatever. No one should go see this movie because they want to see the wiles of romance or film made new. "What Happens in Vegas" is all about comfort. Jack, a slacker dude with an easy smile, gets fired from his dad's furniture shop. Joy, a go-getter lady with a smoothie thirst, gets dumped. Separately, they decide to gamble their blues away in Las Vegas with their wisecracking friends. They happen to meet and, one raucous night later, slacker dude and go-getter lady end up married. Vegas, baby! Oh, yeah, and they win $3 million together outside the buffet, so they can't just get the darn thing annulled. If they want the money, they have to make the marriage work.

What follows is a first- or second-date flick, after which there can be some Cheesecake Factory and maybe a peck on the cheek, no harm done. "What Happens in Vegas" is pleasant enough for all of that (and it sidesteps all that "Forgetting Sarah Marshall" raunch). As "There's Something About Mary" showed, Cameron Diaz has a gift for physical comedy and she gets to showcase it a bit here. She mugs winningly and revels in little moments like when she automatically reaches for the bathroom door only to -- whoops! Find nothing. Someone should give her a real Lucille Ball role she could sink her teeth into.

So what if she's about as believable as a killjoy working at the New York Stock Exchange as Ashton Kutcher is as, well, anything but an animatronic beer can? They're believable as a couple, which is a near miracle in the past few years of romantic comedies in which lecherous old men and doughy schlubs get blithely paired with gorgeous, driven women. Despite the fact that Jack eats his cereal out of a big bowl and scratches his privates ostentatiously, he's a man you might actually see on the arm of a svelte and muscular beauty like Cameron Diaz. Though he can act only a little better than your average golden retriever, he's lovable. And for a by-the-numbers romantic comedy, that's all that matters.