My hubby is so nuts he loves having his ass whipped and the harder the better. I would let him have what I thought was hard and he would tell me to give it to him harder and not to hold back at all. I was afraid I would seriously wound him but he made me do it and his back side started bleeding and I stopped. I don't know how he stood it but he did and actually liked it. He can get very strange with things like that.
