midnight jiberish 

The point past midnight where someone starts talking jiberish just because the person is really tired and should probably go to sleep. It may seem like the person is high, but in fact, he/she just has a severe case of midnight jiberish.

"Why were you reciting Disney movies to me last night?"
"I was? It was probably midnight jiberish."

midnight jiberish by spritehehe May 2, 2008