What is she trying to tell me? Vibrating tail??? : r CATHELP Anyone else's cat do this? She vibrates her tail when she is happy to see me : r blackcats 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 Cat tail signs: What your cat's tail tells you What does it mean when a cat's tail vibrates?