A friend of a friend of a friend tells this story about his border collie mix:
It seems that he is rehabbing a house in an iffy neighborhood in the Benton Park area of St. Louis. For the purposes of this story, we'll call him "Bob."
One night about 11 pm a man comes to the door of Bob's house. Bob doesn't know him and refuses to open the door. The guy keeps banging and banging on the door and won't go away. Bob calls the police. His neighbors call the police. Before they can get there, of course, the door-banging man runs away.
So a cop comes to the door and Bob opens it. Like a rocket, Bob's dog flies through the door, hits the policeman in the abdomen and knocks him down.
Bob is horrified. He screams, "That's a POLICEMAN, you idiot! What do you think you're doing?"
The dog runs into the house, Bob helps the policeman up and apologizes. As soon as the poor cop walks through the door, the dog again rushes up to him, throws himself at the cop's feet, rolls on his back and pees everywhere.
So after the cop's shoes are dried with paper towels he asks Bob, "That's some watch dog you have there, what did he do when that guy was trying to break your door down?"
Bob is ashamed. "He hid under the couch. He only goes after people in uniforms."