My dad has this friend who has a younger daughter Jane, and we have known each other since we were little kids. We teased each other a lot, and since she's the eldest of four kids, and I am an only child, we had a kind of older brother/younger sister thing going. When I was about 16, she was about 13, she came over with her family to play video games.
My aunt (who lives with us) had gotten this foot and leg massager. It's like you put your legs or feet in these grooves, and it will massage them for you. I have big legs, so I only used them on my feet, but Jane has skinny legs, she can put her legs right in there. She started to play around with it while we played Sonic the Hedgehog. Because she had such skinny legs, she could put her thighs in the grooves and as the machine rolled and vibrated them, I could tell she was getting a different thrill out of it than she expected. She was wearing tight jeans, and even though she was still young, she was getting curves in a lot of sexy places.
Usually, she's very competetive with her siblings, but on this day, she was very generous with giving them the controller while she just sat on the couch, letting this thing rub her legs. I have to admit, it was turning me on. After a little bit, she kind of closed her eyes and started moving a little, twisting herself this way and that, and she was breathing pretty hard. I don't know if she noticed she was affecting me, but she didn't seen to care. I was getting real hard watching her toes curl, her nipples get hard, and her squirming with the motion of the rollers.
At some point, I watched her face get really serious, and I knew she was going to come. But then she stopped and said the machine was hurting her. She was really flushed, sweating, and tired. I guess she came, or maybe not, but I excused myself to the bathroom, and within a few jerks of my throbbing dick, I exploded like I never have in my life. Like a river of cum splattered on the bathroom floor, and I had to clean it up.
Afterwards, a wave of guilt came over me. But that night, I jacked off again to the memory anyway. She's like 16 now, and we still are just friends, but once in a while, I dream about her squirming and having an orgasm, and I cum pretty hard. I don't know if she knew what happened, and it's not like I have deep love feelings for her, but it was really sexual all the same.