A couple of years ago my girlfriend [F]25 and I [M]21 went to a secluded (non-nudist) cove to spend the afternoon. After a long walk, upon arrival we found that there was a group of friends who had arrived just at that moment to camp. I was wearing a swimsuit that if I got wet my whole dick would be transparent and my girlfriend a micro bikini, she had a g-string thong that was semi-transparent in front, the top part barely covered her nipples and it was also semi-transparent like the thong, so you could see everything too.
We took a bath and when we came out they looked at us and noticed our swimsuits. Then we started to sunbathe, although things got hot, so much so that she ended up riding my cock with the bikini on but with the thong to the side. After cumming, we got dressed and went home, they didn’t see us have sex since there was a big rock in the middle, but the risk turned us on.
Source: reddit.com/r/gonewildstories/comments/zx84a1/my_girlfriend_rode_me_on_the_beach_with_her_micro