Used to refer to someone who has no general concept of anything... Ever! Such people regularly spit out such heroin soaked random gibberish and ideas, you find yourself standing in confused aw! And just laugh!
Fry brain: if u watch too much 3d tv, when u take the glasses off everything will be in 3d.
Guy: your a dead shit
Fry brain(trying to be clever): I'll spew all over your balls