What is "tamakeri"

Tamakeri (玉蹴り) (lit. ball kicking) is a sexual fetish and subgenre of pornography within which a man's testicles are abused. The genre is also referred to as ballbusting ("bb" for short). Originally popular in Japan, it has now spread all over the world. Tamakeri is the Japanese term, but it is used by many non-Japanese as well. The dynamics of tamakeri are attacks on a specific part of the male anatomy, namely the testicles, and the genre appeals to sadistic women, as well as to both hetero and homosexual masochistic males.