Once upon a time, a messenger boy delivered a bunch of flowers to Marlene Dietrich's dressing room, and surprised her in the nude. "Ooh, they're beautiful!" she said, and gave him a hug. "Well, you'd better run along now -- I hear somebody coming." "Y-you have w-w-wonderful hearing, Miss Dietrich...."
A psychologist once trained fleas to jump when he rang a bell. Then he pulled off their legs. He concluded that when you pull off a flea's legs, it becomes deaf.
A professor used to include in a lecture the sentence "An important thing to know about masturbation is" & then trail off into a mumble. If a student presumed to ask "What?", he would answer, loudly & clearly, "It makes you deaf". As a result, in my time at Caltech, if anyone asked "What?", he got that reply.