Sidney realizes Billy does have an interesting angle to run scams with and he suggests they partner up to take down some of the big games around town. Billy agrees. The partnership meets with many early successes and they share the profits.
They seem to be becoming friends as well as partners, but then they lose to an inferior team, and Billy realizes he's been set up. Sidney was just hustling him all along to get him back for Billy's prior deceit.
Billy's girlfriend intervenes and confronts Sidney's girl about the "betrayal." Sidney's girl says she won't give the money back, but she does encourage Sidney to team up with Billy again and go after some prize money in an upcoming tournament. They win. Everybody is happy.
However, on the ride home, Billy gets mad when Sidney says he can't dunk. He gambles that he can and loses all of his recently won cash back to Sidney. Billy's girlfriend gets mad and leaves him.
To make it up to her, Billy finds a way to get her onto a game show. She doesn't disappoint as she dominates the game and wins a ton of money. This doesn't repair the relationship, however, but it does give Billy some peace of mind.
He finds Sidney again and opens up. Sidney understands. It seems now the partnership may truly become a friendship.