What is she trying to tell me? Vibrating tail??? : r CATHELP Quivering, Wagging, Puffed Up: What is Your Cat's Tail Trying to Tell You? Anyone else's cat do this? She vibrates her tail when she is happy to see me : r blackcats Why Do Cats' Tails Puff Up? Causes and What to Do Kinship A cat's tail is a powerful form of communication that reveals its emotions and intentions. When the tail is erect and twitching, the cat is usually excited or happy, while a straight up Understanding Your Cat's Vibrating Tail Behavior