Fathers' Day (1997)

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.