I take Maddie to work with me everyday and she discovered the spring type door stop behind the door. @ first it scared her when she bumped it, then she started pawing at it and it buzzed as it vibrated everytime she pawed at it. the 1 at work has a rubber end on it so i know it wont hurt her, but she growls and pounces on it constantley making it buzz--she had me laughing so hard i was crying. sometimes i have to remove it just to get my sides to stop hurting from all the laughing. she really likes that silly thing. seems to be her favorite toy at the moment.