We've got two 3 month old mini Australian Shephards, love them to death. We are having a problem with one of them though. He's can be extremely hyper at times which is perfectly fine, but he has a very bad habit of jumping and biting at the same time. He often times clamps down hard with his sharp little teeth on to skin or clothing at the height of his jump, then rips it as he falls back down to the ground. This happens most when he's excited because he's either happy to see us or because he just performed a command well and we are congratulating him. He especially loves to jump at the head when we are crouched down. We've tried several different ways to stop him from doing this. We've yelled no, we've tried yelping as though we are in pain (and sometimes we really are), we've tried ignoring him, we've tried holding him down with a leash, nothing seems to be making an impression on him. Most of the time he just treats it as playing and starts running circles or continues to jump at us. The two puppies play a lot and rough house often, jumping at each other and biting each other, we think this idea keeps getting reinforced as acceptable because of this. Unfortunately we don't have the time and/or the apartment space to keep them apart for the next few months to hopefully curb this. Does anyone have any ideas as to how we can break him of this habit? We are afraid of the other one also picking up this bad trait.