The law of probabilities should have dictated that Cameron Diaz would never make a romantic comedy quite as dire as The Sweetest Thing.

But Sod's Law has stepped in and the result is this toe-curlingly crude battle of the sexes. No-one - least of all the audience - emerges a winner.

Diaz - once the ditzy blonde by appointment but now a thirty-something with a slight hint of desperation - is commodities trader Joy McNally.

She's humliatingly dumped by her pompous boor of a fiance within earshot of friends she's gathered for his surprise birthday party.

Across town, serial slacker Jack Fuller (Kutcher) gets the push from his dad's furniture business and buries the pain knocking back the beers with his best buddy Hater (Rob Corddry).

Simultaneously, Jack'n'Joy hit on the idea of drowning their sorrows in American's desert party city par excellence - Las Vegas. Grating minds think alike.

However, after drunkenly hooking up and hitting the Strip (cue champagne in stretch Hummer), they end up getting hitched in a dimestore wedding chapel. Jack then goes onto win $3m...half of which is claimed by his wife of 12 hours.

Back in New York, a stern judge rejects requests to annul the marriage and tells the reluctant newly-weds they have six months to try to make things work.

Implausibilties are steamrollered out while gaping plot holes are left unplugged in a rom-com that tries to be gross but just ends up grim.

There's a vindictiveness - most tellingly displayed by supporting characters Lake Bell and Corddry - that makes this a pretty unattractive proposition.

If you are going to do nasty it's best to do it cleverly with a bit of wit and invention...but this is just loathsomely dumb.

Diaz is fed philosophical bon mots such as: "I'd rather do nothing and be happy than do something I don't love." Which does rather suggest she'll die a slow, lingering death of starvation with a smile on her face.

Kutcher - no stranger to older women after Demi Moore - never breaks out of one dimension and is reduced to relieving himself in the sink to make any impact.

What Happens in Vegas should have stayed in Vegas.

Tim Evans