I discovered your site quite by accident and, after reading some of the stories, am reminded of childhood experiences I shared with my sister who is three years younger than me.
For a period of about twelve years beginning when she was about five and I was six, we saw each other nude both by accident and by intention on a fairly regular and frequent basis. For example, I would go to the bathroom to pee or dump and she would be taking a bath. If I sat on the toilet we would talk about stuff and, sometimes she would get out to dry herself in front of me. At some point-I cannot remember exactly when-I became aroused seeing her nude or looking up her dress when she sat carelessly around the house.
My brother (who was two years younger than me), my sister and I, often played strip poker when our parents were away. He was not nearly as into the sexual aspect of this as I was. I can remember lying on the sofa behind my sister during the game and masturbating while looking up her naked crotch. In the poker game, when one of us was naked and lost a hand, the others could do anything they wanted to the loser for one minute. I don't remember my brother doing much of anything but when my sister lost I vividly remember spreading her legs, tickling her pussy and examining her entire body and jacking off afterwards-often in front of them.
We were all quite athletic and-among other things-were into gymnastics. Often, while we were in our pajamas before going to bed my sister and I liked to do this particular stunt. I would lie on my back on the floor with the bottoms of my feet raised up over my chest. My sister-sometimes with the help of my brother-would climb up on me so she was standing on my feet. I would have to hold still and she would be balanced on my feet, then I would slowly straighten out my legs so she would rise up to the point that my legs were fully extended and she could barely touch the ceiling of the living room. My favorite part of this stunt of course was the marvelous view I had right up her nightgown.
Often my view was not even obstructed by panties and I could spread my legs (and feet) apart a bit which would cause her legs and feet to spread apart as well. Sometimes I would jack off while she was above me; other times immediately after she got down.
One other activity we used to engage in quite often as we got a bit
older was when she got home from school. We both went to Catholic schools and had to wear uniforms. While I was in High school and she was in Grammar school, I would often get home before her or anyone else and would be sitting on the living room couch watching TV when she arrived. Almost always she would sit on the sofa beside me and we would start to tussle and she would often wind up lying across my lap bouncing her rear end up and down. I responded by putting my hand up under her dress and tickling her crotch.
Sometimes she would place her arm up my crotch also and after a while I would wind up with a sticky mess in my pants.
I remember one time in particular when I managed to get her underpants off and was tickling and examining her pussy and asshole when her girl friend suddenly appeared on our front lawn on her way to the door.
My sister quickly jumped up-she still had her school jumper on-and went to the door to greet her friend. I don't think her friend saw what we were doing. They went outside to play together and I soon joined them in the back yard and pushed them on the swing set-her friend with her short jumper on and my sister dressed the same way but without underpants. It was a wonderful afternoon.
I may add more later as I have many more memories of more advanced masturbatory activities with my sister as we grew up together.