toby is about 16 weeks and he gets very bitey and becomes a little monster when he is in "play mode" ...... they just get so caught up in waht they are doing (playing usually) that they dont realize that what they are doign hurts...... lol.......toby actually responds to "ouch" when he bites to hard (he will give you a nice kiss to make it better...... and then go back to nipping again)..... one thing you need to do is teach him who is boss, if he does this then walk away and ignore him...... this will teach him that when he bites it is no fun for anyone and eventually he will stop doing it....
Currently i am having the problem because my fiance plays with him like that and lets him bite and nip, but not me, he knows i am boss and is USUALLY very well mannered (unless he FORGETS who he is actually playing with)....
Consistancy and patience is the key