'chav face' is an insult to be used against any townie/chav, as both of these species (townie/chav)are stupied and dont understand this insult. it is basicly telling them they are the biggest chav in the whole universe, which in its self, is the worst insult any one could give.
chav: com den man, com den init ill beat u up
'other person': shut up you stupied chav face.
chav: whaaat?> dont use ur big words on me! i dont know wat dey mean dus i man!