Geisha balls , also called Kegel balls, ben-wa balls or lust balls , are usually hollow balls with a weight inside that can roll in the ball. They are inserted into the vagina and serve as erotic toys. The movement of the balls causes an exciting feeling during use.

The original purpose of the balls was to tense the pelvic floor muscles, to move the two against each other. It is said that skilled geishas can bring men to ecstasy with muscles trained in this way.

Kegel/ben-wa balls come in different sizes and weights. The smaller the ball, the harder it is to keep the ball in and the harder the workout. A heavier ball is harder to keep in than a light ball.