Painfully unfunny, What Happens in Vegas is as bankrupt as you'd expect from a romantic comedy born from a tourism slogan. Jack (Ashton Kutcher) has just been fired from his job—by his father, no less. Joy (Cameron Diaz) has just been dumped by her fiancé. Both head for Las Vegas with a quip-heavy sidekick in tow, where they meet under preposterous circumstances, spend a boozy montage hitting the town together, and wake up married in the morning. Then Jack wins a $3 million jackpot off one of Joy's quarters, the two end up in court, and the exasperated judge sentences both to "six months hard marriage" before he'll rule on who gets to keep the money.
Forced into cohabitation, Jack and Joy clash, scheme against each other, and, as the climax approaches, fall in love. Along the way, wacky best friends massacre the audience with forced one-liners, and the two lovers learn a lot about themselves (he's scared of failure; she can't live for herself). It's all very desperate, not to mention textbook (can we please have a moratorium on romantic comedies opening with a shot of the New York skyline?). Only after the end credits start to roll is there a moment of inspired lunacy—and it's not nearly enough to make up for the drudgery that preceded it. In a word: ugh.