Bill, my sister, bet, whom you met at my house, has an old black lab with a bit of border collie mixed in. She sings How Much Is That Doggie in the Window to him and at the end of each line, on cue, he adds a very soprano "Woof, woof". It's really hilarious to watch. He's very broad and when he does it the whole front of his body, feet on up, lifts up with the effort.