A drunk staggers into a bar and demands a beer.
He argues back and forth with the bartender, who refuses to serve the drunk.
Finally, the bartender challenges him to get on the floor and do 20 push ups to prove his sobriety.
As the drunk is doing the push ups, another drunk staggers in. He surveys the scene for a minute, pokes the guy in the ribs with his shoe, and says, "Hey, fella! I think you're girlfriend has gone home."
(adapted from A Guys Walks into a Bar by Michael Lewis)