What chachi said is exactly right. When my Reesie (13 weeks old) gets all crazy biting, I make sure to put a toy in his mouth instead of my hand. Make sure you yell out in a high pitch OUCH when your pup bites you, that's what his littermates would do and he knows that means hurt. Yesterday, I was playing tug-o-war with Reesie and then went to cuddle him and he bit my nose HARD!! No blood, but some redness and it HURT!!! I immediately yelled out OUCH, ignored him, and gave him the toy to bite on!! BE CAREFUL!
Viv