The state of mind in which you think you have monkey powers and decide to jump around from tree to tree butt naked while throwin your feces at people who happen to look at your weird ass.

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.