Back when I was a teenager, I saw a female masturbate for the first time. It was my sister Jen who was two years older than me. I went by Jen's room one summer day, while our parents were at work. I heard noises coming from the room and thought she was on the phone. But when I got closer, it sounded like she was crying. I opened the door and was totally surprised to see her nude, with her legs spread and her finger inserted inside her vagina. She was almost crying with pleasure.

It caught me so off guard that I made a noise in disgust. Jen heard me, but as I was turning away, she yelled for me to come back in her room. I did and Jen made no effort to cover herself. Her boobs were much bigger than mine and her blonde pubic bush was much thicker. She said that if I told on her that I would pay the price.
Jen asked if I ever masturbated myself, and I said I had never thought of it. She said that it was great and it kept her hormones under control. Some of my friends told me how often they did it, and I had desired to try it, but felt it was "dirty". Jen told me to try it with her, so I decided to try.

I took off my pants and then my panties and layed on the bed next to Jen, who resumed what she was doing. I felt my nipples start to get firm, and then felt wetness between my legs. I slid my finger in and it felt so good. I increased my action rapidly, and then added a second finger.

Jen then surprised when she pulled out an eight inch vibrator from under the bed and asked me to try it. It was unbelievable, and I didn't understand what was going on when I felt my muscles tighten up and then felt like an explosion going on in me. It was my first orgasm. Jen took the vibrator from me and slid it inside her pussy until she was almost screaming in delight. Unlike me, Jen slid the entire eight inches inside her vagina.

Jen and I masturbated in front of each other several times that summer. We never touched each other since this was beyond our beliefs. Twenty years later, and two husbands later, I still remember those days with Jen.