Golf ball.

A man entered the bus with both of his front pockets full of
golf balls and sat down next to of all people a beautiful, you guessed it,
blonde.
The blonde kept looking quizzically at him and his bulging
pockets.
Finally, after many such glances from her, he said, "It's golf
balls".
Never-the-less, the blonde continued to look at him
thoughtfully and finally, not being able to contain her curiosity any longer,
asked:
"Does it hurt as much as tennis elbow?"