While banging your girlfriend from behind, secretly pick up a irish red headed midget and throw him on your girlfriend's back and make him lick her arse, while your girlfriend screams in terror.

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.