Watched a porn movie back when you had to rent VCRs at the neighborhood video store. There was a black and white mini movie in one called Pendulum Balls. It looked like it was very old because the lady had some of the unsexiest underwear ever in a porn movie. There was some poor guy and she tied his scrotum in a knot just like that. She kept saying that she loved pendulum balls. I've searched for it many times, but could never find it. My balls cringe just thinking about it.