This happened to me when I was 35 years old.
I went to a place one night to have a few beverages and hang out. It was crowded and people were mingling with each other. My eyes caught a very attractive woman with auburn hair. She appeared to be maybe five years older than me. She was with a guy who turned out to be her husband. Eventually, we started talking and about an hour later, having hit it off well, they asked me if I wanted to go to their place.
They lived nearby and so we went to their place. Inside their house, they said the real reason they asked me over was to see if I was interested in having sex. Of course, I was thinking the guy just wanted to see his wife get laid, but they clarified it was to be a threesome. I had never been in one before and so I was VERY interested!
Almost as soon as I said OK, she simply stripped naked in front of me. Oh, wow, she looked gorgeous! My dick immediately went hard. Next her husband stripped and he was already rock hard, and so I stripped. She was kissing me and feeling me everywhere. At one point I knew her arms were around my shoulders as she was kissing me, but I suddenly felt another hand slide around my waist and grip my dick. It was his hand! I was shocked, but also really turned on too. He told me what a nice dick I had, and then each of them basically kneeled on the floor to look at me and feel me. it was bizarre! She would stroke me then he would stroke me, the whole time talking about my dick.
He wanted to give me oral badly but touching is one thing, and that's another. I couldn't go there. His wife asked me if I'd like to feel her husband's cock too, so I slowly began feeling his big hard dick and stroking it. She was loving it and kept urging us on. It was amazing. I didn't feel all that weird jacking off another guy as he jacked me off. I soon came and he did too. It was awesome!
I had to take some time to recover, and then I took care of his wife doing EVERYTHING she wanted!