Occasional mild vibration of the testes should not damage the testes
or affect their function. An Austrian study found links between
mountain biking in men and decreased fertility and testicular
abnormalities. The connection was the strong and repeated shocks to
the scrotum and perineum (the area between the balls and ass) that the
men were subjected to while biking. However, compared to the
bone-shaking vibrations of bouncing down a rocky trail or jumping
stumps with a bike post planted in your crotch, the minor tremors
supplied by a typical vibrator are quite gentle and non-traumatic.
Overuse of a vibrator on the testicles is not advisable, but the
occasional buzz on the balls shouldn't do any harm.
Reference Sources: What Causes Infertility in Men, University of
Maryland Medical Systems
