Why do cats shake their tails? When my cat’s tail starts going crazy, I watch out lol. He’s usually feeling playful or is annoyed. Either way, I know he’s just about to pounce. It is so funny. If I hold his tail, he gets more annoyed and makes weird and growling type “meows” but he usually won’t pounce on me after that. I just laugh. Cats are just so funny.