A golfer is in a competitive match with a friend, who is ahead by a couple of strokes. The golfer says tohimself, "I'd give anything to sink this next putt."
A stranger walks up to him and whispers, "Would you give up a fourth of your sex life?"
The golfer thinks the man is crazy and that his answer will be meaningless, but also that perhaps this is a good omen, so he says, "Okay," and sinks the putt.
Two holes later he mumbles to himself, "Boy, if I could only get an eagle on this hole." 
The same stranger moves to his side and says, "Would it be worth another fourth of your sex life?"
The golfer shrugs and says, "Sure."
He makes an eagle.
On the final hole, the golfer needs yet another eagle to win.
Though he says nothing, the stranger moves to his side and says, "Would you be willing to give up the rest of your sex life to win this match?" 
The golfer says, "Certainly!"  He makes the eagle.
As the golfer walks to the club house, the stranger walks alongside and says, "You know, I've really not been fair with you because you don't know who I am. I'm the devil, and from now on you will have no sex life."
"Nice to meet you," says the golfer. "My name's Father O'Malley."