Does anyone know why dogs do this? I have a 6y/o male rescue GSD and when we got home today(after being let our of the kennel and pottied) he began walking around my husband and I and clacking his teeth together. It was about 20 seconds and about a dozen clacks. Much like when a black bear will huff at people but with his teeth. There was no aggression and I am baffled as I have never seen or heard of this behavior before.