We had a similar experience, but not so nasty. For many years my wife and I had been visiting a naturist resort in western France, but we kept ourselves to ourselves without being unfriendly and all was well. Then a couple of years back we met a woman on the beach who we knew from a previous "textile" holiday and the two women got chatting. We then got invited to their chalet for an evening meal. We didn't ask whether we should be nude or not, so dressed casually, just to be on the safe side, but when we arrived there we found the woman naked and her husband too. They didn't seem phased by us being clothed, but we decided to join them and shed our clothes. The husband was busy in the kitchen cooking, along with their daughter, so after a quick hello, decided to stay on the porch enjoying a drink. As the two women were chatting, the woman's legs began to open and my eyes were kept being drawn to the pink lips poking out of her short pubes. At one point she caught me looking, but although I was embarrassed, she was unmoved. Anyway we enjoyed a great meal and the guy opened a new bottle of wine and we went back to the porch to drink it. We occupied the 4 chairs, leaving their 17 year daughter sitting on a big cushion on the floor. First she lay on her stomach playing with her phone thing, then she got up to get some head phones. She came back and laid back on her back, resting on her elbows, legs wide apart, showing her bald pussy. She was slim with big tits and a pussy with big pouting lips, a very sexy woman. I tied so hard to look everywhere else but couldn't, I looked at my wife and she was looking too. I instantly had a hard on and I am a guy who "grows" a lot, making a cover up very difficult. I was sitting on a towel and tried to pull it over my cock. To my embarrassment the woman noticed my situation and ask her daughter to close her legs, she replied that this was a "nudist resort" and we should "chill out" and opened them even wider. I sat there with a hard on for almost half an hour until the girl got up and went inside. When we left the girl was lying on the sofa, again with her legs wide open and I walked home with a hard on, to the amusement of my wife. That evening when we got back, we talked about the family and enjoyed to great sex.
To those who say they were embarrassed about their small penis - are you talking about its size when flaccid or when erect?
To the OP, I remember when one of my friends ended up naked in front of the entire school. Later that same night, he and I were talking about what happened, as I felt he really needed to talk about it, and he'd feel a bit better. So I said, "I know, it's mortifying being naked in front of everyone you know, including your closest friends." He asks if he can tell me a secret, and I had to promise never to tell anyone he knew, so posting this story here won't violate the terms of the agreement, but he said "it's not just that I was naked.....I.......I was ashamed about........about my size, because now everyone knows......how small I am." I answered "who cares? I'm quite small myself. You're not alone. And the fact that now everyone knows, leave that to me. I will give them absolute hell!" And I did. Anyone who teased him about either what happened, OR his size (by now, I hope you realize when I say small or size, I don't mean how tall or fat we are), I would make sure they walked away in a complete state of paranoia. Similarly with my other friend, who ended up naked on stage in front of a huge audience, he was ashamed about his size. Bart (the friend from the above story) and I told him not to be, because he wasn't alone. As perverted or creepy or whatever this may sound, we only said theses things to each other to be sure we knew most of us thought we were too small. My point is, don't let teasing about your size discourage you. Most of us feel like we're way too small. And I'll bet you the perpetrators thought the same about themselves. And maybe that's a reason they did that.
Once while we were on a nudist beach my wife needed to go for a pee. She went into the bushes and squatted down.Another woman appeared from nowhere and squatted down opposite just as my wife started to pee at which point the other woman did the same. When they had both finished my wife was invited back with the woman to wipe herself. She ran a mile.
I had very few bad experiences. One I remember was growing up we would go camping at this private club that when we arrived we always got nude. We were always allowed to bring a friend camping any it was not uncommon for my Bros tonbring a guy along and me to bring one of my girl friends along. My brother invited a new friend and he though once we got there all we did was have sex. My brother had to have a quick talking too