Thirty-two-year old Sonny Koufax (Adam Sandler) has spent his whole life avoiding responsibility. But when his girlfriend dumps him for an older man, he's got to find a way to prove he's ready to grow up. In a desperate last-ditch effort, Sonny adopts five-year-old Julian (Cole Sprouse, Dylan Sprouse) to impress her. She's not impressed... and he can't return the kid. Uh-oh for Sonny!