Sack tapping is a slang term for a game where a participant attacks, by slapping, tapping, punching, kicking, elbowing, twisting, or backhanding a victim's testicles. The term derived from 'sack', slang that refers to the scrotum,[1][2] and the activity is a form of groin attack. This sociological manifestation of bullying can result in severe testicular injury that may require amputation as the only form of treatment.[1][3] A reported increased popularity of sack tapping, fueled in part by YouTube videos, and the subsequent increase in hospitalization has concerned parents and urologists.[4][5] It is also called "nut tag", "bag tag", "sack whack", "bell flicking" and "roshambo", the last name coming from an episode of South Park that featured the practice.[6]