crude definition:"brain fart"

An exclamation made when your friends or family are teasing you to a point where you can't handle it anymore and a hissy fit is in order.

Derived from a YouTube user's famed outburst following Britney's lackluster performance at the 2007 VMA's.

When a person wants to make an excuse for his or her stupidity, but wants to make others laugh in the process, so as to take attention away from his or her own dumbass behavior. And, if you're apologizing for your own cranial flatulence (similar to a brain fart), and the person you're speaking to doesn't understand the terminology, you can (temporarily, at least) feel better about your own level of intelligence.