The clumsy and reckless Jack Fuller(Ashton Kutcher) is fired by his boss and father and together with his friend and unsuccessful lawyer Hater(Rob Corddry), they decide to go to Las Vegas to have a good time. Meanwhile the fianc? of the workaholic stock broker Joy McNally(Cameron Diaz) breaks up their engagement because of her lack of attitude. Her friend and bartender Tipper(Lake Bell) convinces Joy to spend a couple of days also in Las Vegas. Due to a hotel management mistake, they are lodged in the same room and later they hang around together. During the night, they get completely wasted and on the next morning, Jack and Joy find that they got married. While discussing to briefly end their wedding, Jack borrows a coin from Joy to gamble in the jackpot machine and wins three million dollars. They question in court the ownership of the money and the conservative Judge R. D. Whopper freezes the money and sentence them to live together with Joy moving to Jack's house for six months and attending regular counseling sessions. Each one decides to make the life of the other hell on Earth to force to get out of the marriage.