I am an older guy, but had a Bi experience in my early thirties. I had fantasized about is since puberty but it was such a taboo for men to discuss, let alone try, and still is verboten I guess. I was newly divorced and started an amazing affair with a woman 25 years older than me. She was attractive and a fairly well known public figure in Canada. It was quite a turn to have hot sex with a lady with a straight laced public, respected image.
One day in bed she shared a fantasy of having two men. As the conversation progressed she became really turned on, especially when I mentioned I knew a guy that was very much into this. Long story short, we ended up at my place twice a month with my friend and had a great threesome time. I loved to watch as she performed oral on him. She knew I liked watching, so she used to put on quite a show. What she did not know is that I was getting turned on because I was envious of her sucking on his sexy erection. It was the same when he mounted her in just about any position. I would fondle myself imagining what it would be like to have his cock inside me anally.
We arranged to meet at my place one afternoon for one of our great threesomes. He arrived first, and then my girlfriend called and bailed due to an emergency. We had already showered and were sitting around in housecoats and continued to chat about our crazy sex lives when I plucked up the courage to ask him how he got into Bi. He was open and easy to talk to about it (my heart was in my mouth!). He sensed my interest and came right out and asked me if I wanted to try it with him. At this point I was so turned on that I could hardly sit still, so murmured yes.
In the bedroom he slipped out of his robe and lay down and I nervously slid onto the bed and knelt next to him and took his cock into my hand and began to stroke and fondle it. It was electrifying as it became harder and harder until it was fully erect. I could hardly believe that this fantasy was finally happening and that the reality was better than the fantasy. When I could resist no more I lowered my head and began to lick up and down his shaft and from time to time and took his balls into my mouth and did my best to swirl my tongue around them. I spent quite a bit of time teasing like this before I finally took the head of his cock between my lips and then slowly swallowed almost the entire length. I started to apply different suction pressures and tongue swirling, occasionally nibbling with my teeth and I was surprised that he came very quickly (CIM). He told me later he was really turned on by a new "conquest". We had already assumed a male-male sex thing where he was dominant and in charge and I was sub which suited me just fine. That's probably why I dabble in BDSM from time to time.