Change direction

Sometimes I wish that if my joke wasn't working, I could just break out the manual and go to the troubleshooting section. And the manual would probably have this to say - If your joke isn't working, it is because it doesn't change direction. All jokes have a "surprise inside" - they will lead you one way and then with their last word or two they completely change direction. The trick is to prevent the audience from guessing the true direction of the joke. How about an example? "In America, anyone can become president. That's the problem." - George Carlin.