A huge fat slutty ugly girl. Their big fat round face is so fat there eyes look like craters on the moon! :D
moon pigs drink heavily, wear tiny size zero slutty outfits like a whore and are so mad they believe they are so hot they could marry brad pitt, easily offended they often turn violent when called a Moon Pig :D
beavis: hey look its a moon pig!
butthead: hur hur Moooooooooon PiiiiiiG
moon pig: come here and say that ill whoop your skinny ass! (throws bottle at your head)