Skinny dipped with a girl and another guy, in a stream. The guy floated on his back with his hard on at full mast. Very subtle indeed. LOL, I got shy and tried stirring up the water so nobody could see my shrivelled pecker.
The most outlandish thing I have ever done naked was crossing a stream swelling with flood water. I had hiked across earlier in only knee deep water and on up the trail. A storm came out of nowhere and I sought shelter in a cave along the trail. It poured for about a half hour. When it finally did I started my return hike. Arriving at the stream I find it swollen with runoff water. I took off my clothes and holding them over my head I waded in now finding the going chest deep. The current wasn't strong as the water was held back somehow down stream. But there were low spots to step off in and I found one of them. So much for keeping my clothes dry.
I use to take walks thru the woods naked all the time in college. I rented a house that had 30 acres for my private hunting use and fun. So I'd ride the motorcycle to the back part of the property and then get naked except shoes and go on a walk about. Of course I'd have to jerk off somewhere along way. Think if I remember my record was 4 hour walk and came every hour.
Walked back to my apartment naked after going skinny dipping in the ocean and then not finding my swim trunks or towel. To this day I still believe that someone took them on purpose and watched me but I honestly never saw anyone around when I stripped. It was a long walk too....
We recently took a vacation that involved stops in about 10 cities. At least once in each city, I stood naked in the window of our room/on the balcony for a little while, sometimes longer, whether we were in a crowded part of town or out where nobody was near. Just felt like showing my naked self to the world.