What Happens in Vegas is a 2008 American romantic comedy film from 20th Century Fox starring Cameron Diaz and Ashton Kutcher. The title is based on the phrase, "What happens in Vegas, stays in Vegas."

Plot

In New York City, high-strung stockbroker Joy Ellis McNally (Cameron Diaz) is dumped by her fiancé at his surprise birthday she threw for him in front of all their friends while at the same time easy-going carpenter Jack Fuller (Ashton Kutcher) is fired from his job by his father, Jack, Sr. (Treat Williams). Both become emotionally distraught and, with their best friends Tipper (Lake Bell), a bartender and Hater (Rob Corddry), a District Attorney, take a debauched trip to Las Vegas. They meet by chance when they are given the same hotel room because of a computer error. After clearing up the misunderstanding and receiving upgraded rooms and coupons to various clubs, they party and drink together and Joy and Jack end up getting married. The next morning, they realize it was a mistake and decide to divorce.

Before they do so, Jack uses a quarter Joy gives him in a slot machine. He hits a $3,000,000 dollar jackpot and Joy reminds Jack that they are married and hence, she is entitled to half of the money. The couple returns to New York, where they attempt to divorce. Their judge (Dennis Miller) declares that the couple cannot divorce until they attempt to co-exist for six months, while attending weekly sessions with a marriage counselor (Queen Latifah). If they work at the marriage but still want to divorce after six months, each will be permitted to keep half the winnings. If either party does not cooperate, the money will be tied up in litigation by the judge.