Toward the end of a summer job at a science field station, I met "Carol", another student. We hit it off really well and started spending every night together in one of the dorm rooms that were now mostly empty. One night while in bed we thought we were alone, but then in walked several other summer students, surprising us literally in mid-stroke. Apologies were offered and accepted (we had not been covered), but after the intruders left and we both caught our breath Carol shared her feelings about what had just happened. And that it had really given her a thrill and that she'd like to explore it further. She expressed that she'd felt humiliated, vulnerable, and empowered at the same time, and that apart from the obvious eroticism she just felt more alive than she'd ever felt before, like every nerve ending and every sense in her body was at high pitch. She wanted more of this. She was conflicted by the humiliation and vulnerability, but told me this just heightened the whole experience. She really wanted to explore this further.
So a few days later it was the weekend and we'd heard about a beach a couple of hours' drive away that was frequented by alternative-lifestyle types. This was at a time when such beaches around had no rules of conduct—not like today when sexual activity is discouraged or even grounds for removal or arrest. So, we headed for this beach!
After hiking down a long narrow trail, we came upon the promised beach, enjoyed by dozens of people, mostly nude. A couple of temporary food and drink vendors, and some sellers of trinkets and other handmade items. No obvious sexual activity, but otherwise a very free-spirited place. Carol chose a spot close to where the trail met the beach, because she wanted newcomers to come upon us without first seeing us from a distance.
We set out the sheet we'd borrowed from the dorms, stripped, and within minutes she had me inside of her. No movement, me just "there", or "in her". Every few minutes a new person or couple emerged from the trail and onto the beach, and passed within about six feet of us. Most kept moving, but some stopped to watch—that's when Carol would start moving a bit, lifting her legs and arching her back. She kept whispering into my ear that she was really enjoying this. But that she did not want guys to start masturbating onto her. She told the few guys that started doing this to please not, but instead to save it for later when they were alone. She explained (all the while fucking), and they could watch all they wanted, but not participate. Interestingly, the guys complied, and were content to watch. Likewise several women watched, although one was derisive and called us perverts and her a slut. Carol's response to that was that she disengaged just for a moment to reposition us, now with her on top so she could look the disapproving woman in the eye, and ask if she'd ever done something just for her own enjoyment. She moved on. The rest stayed a while and encouraged us.
During that first hour, Carol had several orgasms, with no attempt to hide them. She even told some of the watchers to look at her face rather than her body as she came—she wanted to make eye contact with them at this critical moment. I'd already come, but being a guy I couldn't repeat indefinitely like she could! Most of the time I just stayed limply inside, occasionally regaining my hardness. Even without me being hard, she was able to climax for this extended period just because of the thrill of the situation.
After a while, we got up, stretched, and walked down the beach to one of the food vendors. On the way, she said she would bend over slightly with her elbows on the counter and I was to enter her pussy from the rear. This was to see if we could get away with fucking standing up. Well, this worked, and we attracted a lot of attention. She was able to drink a coke and eat a hamburger while thus coupled, but all I could do was dribble coke on her back. Probably because my heart was just about pounding out of my chest, and I had to fight for each breath, even though we were doing slow strokes. (I guess this just shows a basic difference between men and women—she was able to do all of this in stride, while for me this was a life event that might never be repeated.)
Walking back to our sheet we got lots of looks, mostly approving. Once back, I told Carol that I just wouldn't be able to perform for a while. No problem, she said. She lay back on her elbows and invited me to use my tongue. Gladly!! I loved this part, because I didn't have to try holding back, and she loved it because it put her in an even better position to talk with people as they walked by. And the conversations ran all over the place—but mostly "how can you do this?" (answer: Easy, just lie back and enjoy it) or "I wish my boyfriend would do that for me" (answer: why don't you just ask him?) or "you have a beautiful pussy" (thank you), or "did you enjoy your lunch?" (she: it was great, the hamburger man wouldn't even take our money; me: I'll let you know when I'm finished eating".) Carol's answers came between her orgasms.
A few of the guys who watched tried to proposition her. Carol, although naked and fucking right in front of them, told them not to assume that her being naked and fucking right in front of them meant she was available or looking—told them again she was just naked and fucking, and that's all. She said she had chosen her partner (lucky me!) and chosen how she wanted to spend her day at the beach, and that they could also do whatever they wanted and with whom, but not with her.