A cat's body language can give you some clues as to whether or not they're feeling frisky. If a cat is turned on, they may be more vocal than usual, their tail may be held high and quivering, and they may start rubbing against things - including you. Their pupils may also dilate and they may start to drool slightly. If you're not sure whether or not your cat is in the mood, it's always best to ask them directly; after all, only they know how they're feeling!