While out one morning in the park, a jogger found a brand-new tennis ball. Seeing nobody around that it might belong to, he slipped it into the pocket of his shorts.
After jogging for some time, he stopped at a pedestrian crossing and waited for the lights to change.
A blonde standing next to him eyed the large bulge in his shorts. “What’s that?” she asked out of curiosity.
“Tennis ball,” came the breathless reply.
“Oh,” said the girl sympathetically, “that must be painful. I had tennis elbow once.”