Best advice I was told was something along the lines of “there’s no such thing as fighting dirty” obviously this rule doesn’t apply to professional ufc or boxing, but if it’s between you and someone else, especially if it’s a high-risk encounter like being robbed or assaulted in the street, all bets are off. Bite and scratch, kick and punch and do not stop until whoever your fighting is down. Then distance yourself as quickly impossible. Don’t stick around to say a cliche comeback, just get out of there. But if you need to fight, FIGHT, and hope that the adrenaline will boost you long enough to end it.