Pubic hairs on the testicles that have been burned, usually in the dangerous sport of Fart-Flaming. Fart-Flaming is played, either singly, in doubles or in groups (see Mongolian Cluster Fuck) by eating foods that produce immense amounts of intestinal gas, then waiting for a flatus event. As the fart begins to pass the sphincter, the player lights the gas, containing considerable methand and hydrogen sulfide, with a match or a Bic Lighter. If the flame is not extinguished fast enough or if the player is careless, the nut hairs can become singed.
Bill and Ted got together with Beavis and Butthead to play Fart-Flames and ended up with a case of singed nut hairs.