Their large testicles are a representation of fertility and good fortune, and are said to be the source of their magical powers. The tanuki's large testicles are associated with wealth because the Japanese colloquial word for testicle is kindama, which means golden ball. In Japanese mythology, the Tanuki's scrotum can be enlarged to as much as eight tatami mats (one tatami is about 6'x3') and they play them like a drum.You don't say..?
-Japan SAQ (Seldomly Asked Questions)
Kudos to Undercover in Japan for the hook-up.