Gracie always loved playing "attack the leash" where she would grab the leah when it was slack and we were waiting somewhere, I'd wiggle the leash, and she's attack and shake it, growling fiercely, tail wagging a mile a minute! It unfortunately scared passersby sometimes, I guess because she was a huge black dog, and the growling was very enthusiastic, so they would miss the wagging tail and my laughter and ask - from a safe distance. "You okay?"