Pinched from Click and Clack on Car Talk:
Two engineering students had plans to meet for lunch. At the appointed time, one rides up on a brand new beautiful bicycle.
“Wow, that’s quite a machine. How’d you come by that?”
“It was the strangest thing. Yesterday I was walking across the quad when this gorgeous woman rides up, gets off the bike, takes off all of her clothes, and says, ‘Take whatever you want.'”
His friend looks at the bike approvingly… “Wise choice; the clothes most likely would not have fit.”