Temper, temper. Sheesh now whenever you take something away that he is not allowed to have, or he gets tired and cranky he does this. Or he will walk over the the kitchen cabinets and bang his head on that, or drop to the floor and hit his head on the floor. And it is not only once it is two or three times. I try to ignore it as long as he is not hurting himself. he is looking though for a reaction from me, as he will do it and stop and look at me, and then do it again.