A man was walking past some tennis courts on his way to the bus stop one morning when he found a tennis ball on the pavement. Since no one was using the courts at that time, he picked it up and stuck it in the pocket of his shorts.
When he got to the bus stop, he met up with a friend and the two sat down to wait for the bus. As he sat down, however, his pocket shifted such that the ball came to be positioned just about at his crotch and made a very visible bulge. His friend could not help but notice this, and asked, "Uh, are you OK?"
The man realized what his friend was seeing, pointed to the bulge and said, "Tennis ball."
His friend looked very concerned and said, "Oh, man, I am so sorry. I had tennis elbow a few years ago, and I remember how painful THAT was."