Big Daddy (1999)

Sonny Koufax is a slacker, working only part time and hanging around New York, having collected a big payout after a car accident. Then 5-year-old Julian turns up, claiming to be the son of his roommate Kevin. But Kevin disclaims all knowledge and leaves for a work assignment in China, leaving Sonny with the kid. He is about to ship him to Social Services, but then realises that little Julian could help him win back his ex-girlfriend. He becomes an instant daddy, and is a hit with the kid for allowing him to dress and act as he wants. Soon, his ploy is making him reconsider his life, and he forms a real bond with Julian, as well as meeting Layla.