When sitting on a couch with a friend you fart so hard it rumbles all the cushions on the couch. Resulting in a vibration under yours and your friends butt.

A pubic hair piece. A toupee for the pubic area/genitals. In the 1700’s when mercury was used to treat sexually transmitted diseases (Gonorrhea or Syphilis) one of the side effects was the loss of pubic hair. To disguise this condition, that was not cured by mercury, a Merkin was employed.