Cotton panties or underwear that have been farted in so many times that the fabric near the anus becomes partially transparent to the point where the spot is distinctive.

Sunderwear is never shit stained nor is it created by direct contact with poo matter. Rather it is created by the various chemicals in the fart acting upon the underwear fabric.

A phrase to describe someone who is cognitively degenerating. Synonym of "going off the deep end". Can have varying degrees of severity.

Reference to the song "Hey You" by Pink Floyd. The line "and the worms ate into his brain" makes no sense in an otherwise linear and literal narration throughout the lyrics.