An older Jewish man marries a young woman, and they are very much in love. However, no matter what the husband does sexually, the woman never achieves orgasm. Since a Jewish wife is entitled to sexual pleasure, they decide to consult a rabbi. The rabbi listens to their story, strokes his beard and makes the following suggestion: Hire a strapping young man. While the two of you are making love, have the young man wave a towel over you. That will help the wife fantasize and should bring her to orgasm."
They go home and follow the rabbi's advice. They hire a handsome young man and he waves a towel over them while they make love. It doesn't help, and the wife is still unsatisfied. Perplexed, they go back to the rabbi and let him know what happened. "Okay," says the rabbi. "Try it in reverse. Have the young man make love to your wife, and you wave the towel over them."
Once again they follow the rabbi's advice. The young man gets into bed with the wife, and makes love to her with great enthusiasm while the husband waves the towel. The wife has an enormous, screaming, room-shaking orgasm. The husband smiles at the young man triumphantly and says, "See schmuck! THAT'S the way to wave a towel!"