We don't really sexually stimulate Katie that much, because she is our best trained HuCow and she will accept any handling, massaging, and milking without problems. She can take the hardest milking sessions without any bondage, although we like to keep her chained up (it's really the best to keep your HuCows collared so you can easily move and attach them to walls or frames).Sexual stimulation is mostly for HuCows who are still in training, it helps to associate arousal with milking pain so their brain gets reprogrammed to LIKE milking sessions. Katie doesn't need all that, but we still love to reward her occasionally because she is our best HuCow with the most developed udders and she's a fan favorite! Who doesn't love a Katie session