Just to add to this... I am quite rough with Payton when we tug, I smack his sides and push him around. But he never bites or nips unless it's an accident, and yes, if he accidentally gets me, the game is over. Self control is something I've worked on a LOT with him, and it's out of necessity. When you "poke" him and he bites you - "nip" or otherwise - and you then go back to a rousing game of tug, you've just rewarded him for biting you. I agree that you have inadvertently encouraged your dog to redirect on you. No more of that in the game.