Fathers' Day is a 1997 comedy film that was directed by Ivan Reitman and starred Robin Williams, Billy Crystal, Julia Louis-Dreyfus and Nastassja Kinski. It is a remake of the 1983 French film Les Compères.

In the film, a woman (Kinski) gets two former lovers (Williams and Crystal) to help her search for her runaway teenage son by telling each man that he is the father. When the ex-boyfriends run into each other and find out what's happening, they work together to find the teenager and determine the identity of the actual father.

The film features an appearance by the musical group Sugar Ray.

Mel Gibson makes a brief uncredited cameo appearance in the film. IMDb credits him "Scott the Body Piercer."

In South Africa, this film was released as What's Up Pop's? at theatres, as the distributor decided the title would be more appropriate for the local market. The name was subsequently changed to What's Up Pops? for DVD release, when they realized the incorrect use of the apostrophe.

Jack Lawrence is a smart allec lawyer who is one day visited by an ex-girlfriend who tells him her kid was his. Enter Dale Putley, a depressed goofball who is also a writer, meets with the same ex-girlfriend who tells him her kid is his. One day Jack and Dale meet and discover what had happened: they've been told the same story and now there's a question of who the real father is. They learn their son is following a rock band called Sugar Ray around. So Jack and Dale hit the road to Sacremento and find their drunk, lovestruck son. Soon after they bring him back to their hotel room, their son escapes and Jack and Dale must use teamwork to find him again, bring him home, and find out which one of them is the real father. Written by Dylan Self

After Scott has a fight with his father and runs away and when his father refuses to go after him. His mother, Collette, then goes to one of her former boyfriends, Jack, a lawyer, and tells him that he's her son's real father. Jack initially refuses. So she goes to another boyfriend, Dale, who goes off looking for Scott. Eventually the two men meet and realize that they are looking for the same boy and that Collette told them they are the boy's father. What follows is a mad chase, cause the boy doesn't want to go back. Written by rcs0411@yahoo.com