Gracie loves her tennis balls too. She likes to play keep away with me on the loveseat, she sits and gnaws her toys in the corner with her hiney facing me. I trick her sometimes by having two balls out at the same time. She always wants the one I have and drops the one in her mouth and jumps down and goes after the one I toss. We can keep that game going about 6 exchanges before she tires of it and just doesn't bother going after the tossed one anymore.