My mom, sister, and myself all lived in an apartment in New York. There was only two bedrooms so my sister and I had to share a room. We used to share a bed too, but then we bought an inflatable air mattress and I use that. My sister had a nice figure and she was 15 at the time. I was starting to have a figure, and I was 13 at the time.
Every night when it was bed time, we would both lay down on our beds. My sister would always listen to her music before she fell asleep, and I would play my computer or something. I noticed that when she turned the music off and supposedly went to sleep, she would be slightly moving, and breathing weird.
One afternoon while our mom was at work and we were off from school, we were both in the living room watching television. I was curious about what she was doing at night, so decided to ask her. So I did. She was flush red, and did not say anything to me. I asked again and she said that she was masturbating. Of course I did not know what that was so I asked her. She said that it is what you do when you need to feel relief. I was drawing a blank. I did not know what she was saying. I told her to show me. She sighed and took off her clothes. I was shocked because I did not expect her to get naked. I did not know what to do and I just sat there. She told me to take off my clothes and get on the floor too. I was a bit nervous because she was more developed than me. But I got over that and did as she said. She told me to follow her, and she started rubbing her clit. So I did as she did and I started to feel this good feeling 'down there.' I liked it so I kept going.
It wasn't long before my sister started shaking a little bit and breathing harder. I asked what was wrong and she said nothing. Then all of a sudden she moaned a little and was panting. I asked what was wrong again and she said 'It felt good.' So I kept going with her just watching and eventually I felt that same wave of pressure, letting a few moans out.
I liked it very much and I have ever since. We did it together in our room almost every night until she moved out for college four years later. This has been one of the best experiences of my life!