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1.
an ugly girl and/or the face of an ugly girl, can be used at both

originates from Windsor Ontario

i believe it was derived from mug meaning face, and hit being an abrasive, ugly sounding word
-Dude that chicks a hit mug.
-(ugly girl walks by, someone yells) HIT MUG!!!!
-Dude, that chicks got a hit mug!
by York March 28, 2004