It was unplanned but worked out very nicely.
Recently, I was using an exercise bike at the gym. It's a machine that has a seat very much like a regular chair, and pedals in front. There are hand-holds next to the seat. I was holding onto the handles, and my elbows were pointing out behind me. After a few minutes on the machine, a girlfriend of mine spotted me in the crowded gym. She and I are good friends. Very good friends. She and I, along with our boyfriends attend the same swing parties together. She came over to chat while I huffed and puffed on the machine. Well that's exaggerating a bit. I had set the machine at level 5 so I wasn't working very hard at all.
Anyway, she stood close at my side and slightly behind me. Her crotch was positioned very close to my elbow. As we talked, she put one arm on the top of my seat back and intentional or not, my elbow made contact with her crotch. She spread her legs just enough to let the back of my arm, just above my elbow, to press on her pussy. At this time, I realized what she was doing and pressed my arm firmly back against her. Because I was pedaling, and I was still gripping the handle by my seat, my elbow was flexing slightly up and down and I masturbated her like that while we chatted. And we were not shy about our conversation... we were talking about our most recent swing party and what we wanted to do with whom at the next party. I'm sure the people exercising near us were listening in. After a few minutes, I recognized the onset of her coming orgasm and right there, amidst all those people, she came, against my arm, with my active encouragement and help. I sped up my pedaling to help her along.
After she came down from her orgasm, she said how incredible it was. I was slightly nervous, hoping the nearby people hadn't noticed what just happened. I turned my head to look around to see everyone's head turn away at the same instant. They were watching, no doubt about it and they saw it all. After she left to go back to her exercising, everything went back to normal as if nothing had happened.
Except for one guy who was on the elliptical right behind me. He came over and struck up a conversation with me, mostly small talk, but eventually, and I expected this was what was on his mind, he asked me about my swinging, if any of that is really true and I told him it is. And he asked if he could get invited to the next party. He is a really nice looking stud and I said he would probably have to bring a girlfriend and he looked a little disappointed. He doesn't think his girlfriend would go along with it, but he said he'll try. Or maybe try to find someone else who might go along. We exchanged phone numbers and went our separate ways. If anything develops from that, I'll write about it here.