What's your favorite joke with an unexpected punchline?

[Answered on Quora.com by Joseph Aspler]

It was a dark and stormy night. A man rushed into a roadside bar and demanded a drink. Two of them.

The bartender said, “You look like you’ve seen a ghost”.

The man replied, “It was terrible. My car broke down at the side of the road. I needed a ride, but it was so foggy. Finally a car appeared out of the mist. I jumped into the back seat - but there was no driver. A disembodied hand appeared out of the fog to steer the car as it moved without making a sound. I sat there, rigid with fear. Finally, I saw this bar through the fog. I jumped out, ran for my life, and here I am.”

The bartender nodded with sympathy. Then two men walked into the bar, looked around, and said, “hey, there’s the idiot who jumped into our car as we were pushing it”.