The first day they go fishing, but they don't catch anything. The same thing happens on the second day, and on the third day. It goes on like this until finally, on the last day of their vacation, one of the men catches a fish.
As they're driving home they're really depressed. One guy turns to the other and says, "Do you realise that this one lousy fish we caught cost us fifteen hundred bucks?"
The other guy says, "Wow! Then it's a good thing we didn't catch any more!"