Big Daddy (1999) on Netflix

Sonny Koufax graduated from law school years ago but chose not to take the bar exam. Instead he works as a toll booth collector, and spends his day loafing around. One day his grilfriend decides that she has had enough, and tells Sonny that things have to change or else it's over. When Sonny's roommate Kevin leaves for China, a boy is dropped at their place and is told that he is Kevin's son but Kevin doesn't know his mother. Sonny takes care of him, and after spending sometime with him decides to adopt hoping that maybe his girlfriend will be impressed. But when he learns that she has a new boyfriend, Sonny tries to have the boy sent back to his mother but when he learns that she died and that he would be sent to an orphanage, Sonny decides to take care of him.