Adam Sandler is Sonny Koufax in ‘Big Daddy’, a 1999 American comedy film directed by Dennis Dugan and written by Steve Franks, Tim Herlihy, and Adam Sandler based on a story by Franks.
It is about an easy-go-lucky guy named Sonny Koufax, who gets dumped by his girlfriend for not accepting responsibility. Sonny then gets a crash course in personal responsibility by adopting a five-year-old boy named Julian who appears on his doorstep.