When the gruesome twosome think that they have to protect their imaginary bones, the pantry door, the dirty plate or the gum in my purse- they will start growling, showing teeth or even fighting. That has got to stop! So when it starts I give a loud "Ah-AH!" a mean posture and dirty look and let them think hell is raining down on them for 3 seconds and I put each of them in seperate corners (the sin bin) for a few minutes. That seems to be working.