Subject: wave the towel!
An old man marries a much younger woman. However, no matter what he tries, he can never bring her to orgasm.
He goes to a sex therapist and tells him his problem.
"What you've got to do is encourage your wife to fantasize," says the therapist.
"Hire a young man to stand at your bedside and get him to wave a towel while you have sex."
Though puzzled, the old man agrees to give it a go.
He hires a young bodybuilder to stand over the couple the next time they have sex.
The bodybuilder stands by waving a towel but still the wife won't orgasm.
The old man goes back to the therapist, who suggests the old man and the bodybuilder swap positions.
That night the bodybuilder and the wife have sex while the old man stands at the bedside waving the towel.
In a very short time the wife has a series of earth-shattering orgasms.
"Hah!" shouts the old man, slapping the bodybuilder's butt.
"Now THAT'S how you wave a fucking towel!"