True story, to the best of my abilities. Since I have jerked off to this plenty of times since, I remember most of what happened pretty well.
My sister, Kelly, is four years older than I am, and my oldest sibling. We have never been close. She hated living with my two brothers and me and moved out when she was 17, so this night must have happened not long before she moved away.
A little background: Before I was born, my parents put an addition on our house and turned their old master bedroom into two rooms, one bedroom for Kelly and one for me. My parents and my two older brothers slept in a separate, newer area of our house, which left Kelly and me to ourselves. They added a new door and a closet to my room, but because of the heating and air conditioning vent in the center of the master bedroom's ceiling, my dad had divided the room down the middle with a wall that did not quite reach the ceiling. There was about a foot to a foot-and-a-half of open space the entire length of the wall.
The ceiling was tall but I used to climb up there and look down into my sister's room, spying on her. She hated that I could see into her private stuff. I would tease her from the wall and sometimes climb over it and snoop in her underwear drawer and CDs when she was out of the house. She would yell at me whenever she caught me. Although I guess I knew she was cute (my friends certainly thought she was hot), basically she was just my older, bitchy sister who fought with my brothers and me. But, being my only sister, I was fascinated by anything of hers that could help me to understand girls better.
My bedtime was earlier than Kelly's, so when she came to bed, her bedroom light, coming over the wall, and her noises and movements, which I could plainly hear, would sometimes wake me up. I would listen to her get ready for bed. I would visualize that she was now taking off her shoes, and now her jeans, and now her bra and panties. I would think 'now she is completely nude.' She would read, study, or listen to music at very low volume. Sometimes I would ask her what band she was listening to.
At some point I began to be aware of strange, wonderful noises coming from her bed at night. But it took a long time for me to catch on that she was masturbating. It was not difficult to hear her because our beds were right next to each other in adjoining corners of our rooms, separated only by the partial wall. Sometimes her bed would actually knock against the wall as she moved around. And I could smell her perfume and hear her sleeping. I would lie awake at night and listen.
When Kelly was being nice to me, she would talk with me between our rooms. Usually, though, she was pretty mean. If I asked her a question she would tell me to shut up, mind my own business, and go back to sleep, threatening that she would tell my parents that I was still awake. Sometimes she made me cry.
One summer night, though, when I was probably 13 and was old enough to be masturbating, I heard her breathing and moaning and sighing after she got into bed. I knew it had something to do with sex, but I never really thought she masturbated like I did.
That night, Kelly got fairly loud, whispering all kinds of naughty things to herself. She must have been really horny. I tuned in and became turned on. I took off my pjs and started playing with my cock, not actually knowing that she was masturbating. I wanted contact with her, so I took a chance. I asked her if she was awake. She responded that, yes, she was, and asked me why I wanted to know. There was something very breathy and heavy in her voice that made me excited. I asked her if she was OK. She wanted to know why I asked. I said because I could hear her moaning and that her breathing sounded different. She laughed and said she was fine. Then she asked me if I could hear anything else.
It was so unusual for us to be talking, especially with her so eager and soft-sounding and sighing like she was. I listened hard and told her I could hear her breathing and sighing. She laughed again as her breathing and sighing got louder. Then she asked me if I could hear anything else. It was something of a dare. She sexily asked me if I could hear her push the sheets down (as she pushed them down); if I could hear her take off her panties (as she slipped them down and dropped them to the floor); if I could hear her moving on her bed (as she began rhythmically to move); and if I could hear her bed move and a wet, sloshing sound. I told her I could hear all of those noises. She replied 'Mmmmmmmmm.'
I asked her what she was doing. She told me she was hot and was just trying to get cool. She said that I should just go back to sleep. After a minute, she said, 'You know, I can hear you sometimes too. Like right now, I can hear you.' She told me she that she knew what I was doing. I stopped masturbating and she laughed, saying that I did not have to stop because of her. She told me she had heard me many times. At that point I did not know if she really knew I was masturbating but I was happy she was OK with my moving around and making noises, so I continued stroking my cock, adding more spit for lubrication. She said 'I heard that. I heard you spit into your hand. I know what you are doing.' At that point I was not caring what she heard because I was really getting into my stroking. I added more spit and beat my meat faster, making more fucking noises. She said 'I can definitely hear that.'
Kelly asked me more questions, as her breath quickened and her voice got deep and throaty. I could hear her bed rocking on the springs, with her grunts and breathing to match. She asked me if I had ever heard her before. I said 'hear you what?' She said, 'You know, doing what I'm doing.' I said 'maybe sometimes.' She said that was cool, that she couldn't help it sometiems and that she didn't care if I heard her. She said it was fun sometimes to do it with someone else.
She asked me what I was thinking about. (I was thinking about her fingering her pussy.) I lied and told her 'nothing.' She said that was cool and that we should just stop talking. At that point she got even louder, and I knew for sure she was masturbating just like I was. She was making definite fucking noises, grunting with each thrust. I was shocked but extremely turned on. She must have been too.
She gave me a vocal show. She moaned and sighed and grunted, whispering very suggestive things. I wondered if she was talking to me or to herself. I liked it a lot. It was the closest we had ever been. I responded by moaning and sighing along with her. She talked us both to orgasm. At one point she whispered, 'I'm almost there. Are you almost there?' All I could do was to moan louder. When I came I came very hard and loud, grunting and bucking on the bed. I nearly peed myself. When she heard me come she said 'Oh my God! Your'e comming.' When she came, she came really loudly, crying out. After she came down from her high, she asked me if I was going to sleep now. I said I was. She turned off her table light. I asked her if she was done now. She said 'Yes, stupid. Can't you tell? Now go to sleep. And don't tell anyone about this or I'll kill you.'
Although we listened to each other get off a few times after that, we never engaged again in conversation during mutual masturbation. She was still audible. I was still audible. Sometimes I was really loud, and she would tell me to keep it down. Sometimes she would hear me and masturbate with me. Sometimes I would hear her and join in. But she always rebuked my questions, no matter how loud she got (and sometimes she, too, would be pretty noisy). There were times, however, after she and I had both come, when she would say 'Goodnight.'