I’ve never done this before and I’m generally open for new experiences (except drugs and other bad stuff of course).
It shouldn’t be at “just” any time, but rather be something special to remember – sounds weird, huh? Well, let me explain…
I’d like to do it during the night or very early in the morning when the mist hasn’t cleared yet and the first sunrays touch the earth (ideally, I wake up early on my own and don’t have to set my alarm clock). It should be in a lake (don’t ask me why, in my imagination, when I read the words “skinny dipping”, it’s always a lake that pops up on my mind). Additionally, it’s slightly raining – just to draw this picture in my head makes me all warm and fuzzy.
It’s quiet and peaceful… Just me (ok, maybe one more person – preferably male xD – at most). Got the picture stuck in your head now? Good, then you know what I’m talking about ^^

