When I was in 4th grade I was like 10 years old girl, a bit chubby, no hair yet but my breast was already beginning to grow. I had a neighbour boy I was friends with and we hung out all the time, even sharing a bed and an occasional shower, never sexual, we always just shared, no matter what. He even wanted me to keep him company on the loo, so yeah, I watched him pissing and shitting and the like.
What I want to tell today was an episode, we were both 10ish and his dick was still hairless such as my vagina. We showered together at his house and afterwards, his parents snapped a pic of me, him and his little sister, all nude but wearing a towel. Somehow, in his room, we dropped the towels and took his camera and started taking pictures of us nude. In the beginning whole body, at the end, I ending up on his bed, legs spread apart, opening my lips for him.
Too bad, that day the film was already used so we did not get real pictures, which I today (as I am 38) really regret.
So, yeah, that was it. Oh wait, not quite. in the night, he wanted to rub our bums together nude which we did, but when he wanted to rub his penis at my vagina, I declined.