Lifting the bulldog flaps to look at Butch's long array of pointy teeth was like raising the hood on a muscle car to check the engine.

As we approached the other lady with her little dog, I kept a firm grip on Butch's leash, and told him to " be nice" and ,"be good". So Butch wagged his tail in a friendly manner, and his mouth was closed, and demeanor cool, that is, on the side of his face closest to me. But something was wrong. I leaned over to check the side of his snout closest to the passing little dog. Sure enough, the bulldog flap on that side was lifted up and back like a raised curtain, in a frozen snarl, brandishing a threatening row of sharp, white teeth. Bad dog.