Growing up, I had a cousin that you could tell was much more fem than any of his brothers.
There were occasions where Mom would babysit them, usually with us staying at their house for the duration (3-4 days to a week).
I had to share a bed with him when this came about, and he introduced me to a few things. No sex or sucking, but a lot of touching and humping.
We were probably 7-8 years old at the time, and I had no idea what we were doing, but that feeling of a having a very hard yet still small dick was very exciting!
Although I had lots of fantasies about it, that was my extent of my experience with anything that could remotely be considered bi or gay until I was in my middle 40's.
I was getting together with the wife of a married couple when the husband decided he wanted to join in on the fun. But his idea of "fun" was to have sex with me!
Over the course of several weeks, we chatted often about it; sometimes with the wife, sometimes not.
Then the time came for us to actually meet for our '3-way', and to say he was eager was an understatement!
He had my dick in his mouth within seconds, and I started touching and rubbing his dick. After a few minutes of that, he wanted me to go ass up so he could rim my ass, and I remember thinking that everything was happening very quickly, and I was going from being a practical virgin to likely getting my ass fucked in just a matter of minutes. But he never attempted to penetrate me.
He wanted to trade positions and have me fuck him from behind. I did penetrate him, but he was crying that it was too big and for me to take it out. So we spent the rest of that night trading oral in various positions, but neither of us wound up cumming. As matter of fact, he was dysfunctional, and never got to full hard over 3 days of me trying.
We met a couple or so more times after that, and I did wind up fucking him missionary and cumming in his ass. After his wife joined us, he wanted to reciprocate, but he couldn't get hard enough to penetrate me. So he rubbed his dick up and down my crack while I ate her pussy before I fucked her.
