To verbally abuse a person to nonexistence usually because that person said something completely retarded.
I said "I'd trade Reyes for Holliday in a New York minute" and everyone MGF'd the fuck out of me.
mgf is machine gun fellatio except a different idea slighty. It is basically blowing your brains out, as that dude in Fight Club tried to do.
Dude why don't you fucking mgf already, it'd make our lives and your own better.