Term adj. Used in both a positive and negative manner as a descriptor of the person being spoken to or an object in question and also to describe ones state of frustation.
Yo mufucka you better back your ass up.
Hey homey hows ya mufuckin ass been.
Mufucka i just stumped my toe.
Aint this a mufucka.
When someone is so ugly that they simply cannot be described with actual words, so one decides to simply say "mufuckin uhhh" in place of an adjective to describe their vulgar appearance.