Watching my parents
My bedroom and my parents' bedroom had a closet in between. I found out that there wasn't a wall between the backs of the closets. After hearing my parents having sex one Friday night, the next Friday night I opened the closet door in my parents' room and then went to my room and got in the closet where I could look through the open door and see their bed. After they came in I watched as my mother undressed and I saw a naked woman for the first time.
I watched as they kissed and then my dad got between my mother's legs. I had a great view and could actually see his dick going in and out of her. After my father finished he moved down her body and licked her until she came in a great shaking moaning orgasm. I watched them every Friday night for nearly six months.
Nothing was ever said to me but after that whenever I left their closet door open, my mother would close it when she came into their bedroom and I never got to watch them again.