(n.) The condition of having one's back ache, as a result of arching the lower spine inward in order to achieve the look of a larger butt while twerking

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.