My sister is two years younger than me, and I'm pretty sure she masturbates too, although I never saw her doing it. One day, I was jerking off as I looked at porn sites on my computer when my sister walked in on me. We had just had a big fight earlier during the day and she was really pissed, so in order to get back at me, she called our mom who just happened to be coming upstairs on the way to her room.
I was still sitting on my computer chair with my boxers down to my ankles and still with a hardon when our mom walked in. There was no doubt as to what I was doing, but my sister still told mom anyways. First of all, she said: 'So what? What's wrong with your brother jacking off?' She then looked at the computer screen and said: 'Close all those sites.' I did so without hesitating. She then called me to her room and my sister was still kind of confused but figured I was gonna get yelled at for watching porn on my computer. I followed my mom into her room, and my dick was still kind of hard, but not as it was before. Mom then said she had something better for me, and picked up a small shoebox and made me follow her downstairs to the tv room. She opened it up and showed me about 10 porn dvds.
'You need to watch some real porn, here.' She then popped one on, and told me be comfortable again, but she also wanted to stay and watch, cause it had been a longe while since she saw any of those. So as I got hard again, I began to jerk off in front of my mom and she was quite happy with what she saw. She began putting her hands down into her sweatpants, and removed her tanktop a couple of minutes later.
I told her I was about to cum, and she asked when was the last time I had masturbated. I said it had been about a week ago. She then said: 'Oh wow, then you must have a lot of cum in there. Come over here.' And she asked me to squirt it all on her tits!! So I got up in front of my mom and began to jerk off right in front of her beautiful boobs as she fingered herself. When I began groaning and moaning she took hold of my cock and jerked it even faster, leading to the best orgasm I had ever had up to that day!
After we were done, she told me I could watch it whenever I wanted, with whoever I wanted, and jerk off as much as I wanted anywhere around the house, and that she'd talk to my sister about it too. Turns out my sister loved the talk with our mom since she now joined our fun, and the three of us masturbate together many times, either watching porn or just looking at each other. I do it alone with my sister sometimes as well, or just with my mom. I also know they do it together too, and the day I caught them was awesome!