This is a sexual act that consists of one taking the other's testicles (balls) into his/her mouth and sucking each one quickly and separately and spitting them back out, creating a pleasure-filled ball-sucking experience.
Michael particularly enjoys having his balls sucked on, so he loves it when his girlfriend
performs the ball vacuum.
When it becomes boring in the bedroom, Randy and his girlfriend
Elizabeth like to spice things up by engaging in the ball vacuum.