I have had sex on my period with my ex husband. Only when my flow was light. Like near the end. Other wise I was to crampy or uncomfortable to enjoy it. He always knew when it was okay and yes, i would be very horny. He never went down on me but oh well. I wish my BF now would do this, but he is squeamish about blood. Go figure! I agree about going down and focusing on her clit. Makes it better and much easier, but once again it depends on her cycle and the flow.