A person with a face that instantly pisses you off the moment you see it and you have to fight an incredible urge to smash him or her in the mouth.
Examples of fuck faces would be spoiled rich kids that smirk, Irish kids with the pushed-in pug and freckles, and teenagers who look down their noses at you.
President Bush is a real fuck face.
Can Tommy O'Leary fit anymore freckles on that fuck face?
Don't eyeball me fuck face or I'll knock your ass into next Tuesday!