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