lol... it was like pushing up against a wall until he relaxed his hole and my head popped into his tight sphincter... I think we both said something like "oh fuck!" It was like someone was squeezing my head in a fist.
I learned later he relaxed his sphincter by pushing like he was defecating. Only difference was that something was on the way in, not out.
BTW he was on top controlling how much of me he took how fast. He squealed when he pushed down and took a little more of me. My head slid into his rectum which was not as tight but still quite snug. The tight band of his sphincter slid further down on my rod as he worked his way on. He got off several times and applied more lube. I had to hold the base of my cock to keep him from injuring me.
Took a while but he worked his way all the way on. With all the squealing, whimpering, gasping and moaning I wondered if he was dying. Once he was comfortable enough he bucked and romped until he squirted all over my chest and belly.
I was 22, he 20. It was 1984. HIV/AIDS was hitting planet sex hard. The body count grew by the day. Reminiscent of covid today.
Men over women because of it? No, but I did start topping guys now and then when opportunities presented themselves.