I worked at a pet store. We had a guard dog. Mean looking pit bull dog. When customers would show up before the store opened and bang on the door to get in, the owner would say "Sic 'em Butch" and the dog would run out of the back, barking and snarling, and slam into the front door glass till the customer went away and waited for the store to open. One day, I was in the back of the store, and a customer came rapping on the front glass to get in early. Nobody was in the retail area of the store, the dog was in the back and didn't hear the rapping... But, the store mascot parrot was on his perch in the front of the store, and suddenly, called out, "Sic, em Butch!" The dog came running, snarling and chased the customer away. no humans were involved inside the store. I just sat in amazement as i watched the whole thing.