Go to bed uncle fred. Your drunk again
He shouldn't have his hands on your rear. Are you still a virgin? Or has he taken that too.
As you're a legal adult, it should be up to you whether or not you want to deal with that. I personally wouldn't have it if anyone tried spanking me, as I'm 18. That's not saying much though because if someone tried spanking me at 16 I probably would have knocked them out then, too.