A person so hideous they are not just fugly, they have been elevated to the highest tier of ugliness. It is a top echelon of raunchiness, no other word can fill. Only to be used as a last ditch effort to describe someone.
"There's the good, the bad, the fugly, and then the dreaded, muthafugly."
"That chick is so muthafugly, my eyes burn."
It was made by the legend himself MythyMoo.
He used this amazing line when he was playing G-Mod.
He described a beautifully burned corpse as a "Crispy Muthafucka"
Person 1 "The man was burned to death"
Myth "he's now a crispy muthafucka"