Cat tail signs: What your cat's tail tells you she always vibrates her tail at this exact spot very.. confused?? anyone else experienced this? It looks like they are vibrating. When a cat's tail shoots straight up and quivers or rattles at the tip, it is the highest form of excitement they can show. It's a Why Do Cats Vibrate Their Tails? Reading Your Cat's Body Language Kinship How to Read Your Cat's Tail Language