In the first half of the movie, Brian (Tom Cruise) and Doug (Bryan Brown) are at the basketball court. Brian is shooting, and Doug is mostly just watching as the two talk about Brian's relationship with Coral. During the conversation, Brian says:
10 bucks behind the line?
Which sounds like he's proposing a bet - i.e. if Brian makes the shot, Doug will give him $10, whereas if he misses, he will give Doug $10. That's all perfectly normal, and consistent with betting-themes later in the movie.
Here's where it gets confusing: Doug then responds with:
Sure - shoot 'till you miss
I gather it's meant to sound as thought Doug is "upping the ante", but I don't understand why or what Doug is proposing here. If it means "Brian can keep shooting, and Doug will give him $10 for every shot he makes until he misses one" then it would now seem to have no risk involved for Brian, and no chance of a financial upside for Doug. Is there another explanation? Is it possible this is a script writing oversight?