Term pertaining to the deleterious effect of the sweat from your nut sack upon surrounding tissue and material. Nut rot causes your underwear to prematurely fail in the crotch area immediately beside where your sack rides. Nut rot becomes visible as a tan or brown stain in the area where your crotch is on the inside of the underwear. Next, the seam and the stretchy elastic gives way and eventually the entire crotch area of the underwear gives out and your nuts hang out from beneath your underwear in the area where the underwear material used to be. Nut rot also affects the skin of the crotch in cases where a person uses poor hygiene and / or lack of bathing or showering. See crotch rot
Damn, when Frank was on the campout, his nards hung out of his skivvies. He must have major nut rot in his tighty whities.