When you hear beeping sounds as if your pager has gone off, when in fact it hasn't.
When you feel a vibration like the pager went off but was only the cars engine reving mimicking the feeling.

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.