I had taught my Dad's black lab to crawl, I also taught her to roll over. Eventually I could get her to low crawl to me with a couple combat rolls mixed in.
I have a border collie mix, when she was a puppy i would say "ATTACK!" and she would run over and start chewing on my wifes older dog. My wife wasnt too happy about it, so I had to stop with that trick. Now we have a young German Shepherd when you say "outside" she attacks my border collie...my wife says it serves me right for teaching my dog "ATTACK!"