She wanted to see penis and she saw it coming.
When I was 13 and my sister 16, she had spent one day acting hornier than I had ever seen her. She kept walking around wearing less and less. It was just me and her at home so she probably thought she would push it even further.
She came out of her room and she had panties on which showed her pussy lips and her pubes were trimmed but sticking out of the top. Her nipples were erect and some of the areola was showing from the edge of her bra.
She said to me 'Sorry, it's hot and I had to undress a bit'. It was then my penis started to harden up. Hey, I'm a guy!! She told me to undress a bit so she didn't feel so uncomfortable. I took my pants off which showed I had a hard on. She pointed it out to me that I had a hard on and told me it was ok. It was then she asked to see it. She said she would show me her boobs and I agreed. To speed the story along, within about five minutes we were naked.
I asked her why her panties were so wet and she explained she needed to masturbate. I asked her to show me what that was. She immediatly obliged and orgasmed quickly. I knew I had to do so as well but I was too nervous. She asked me if I play with myself. At first I lied and said no, and then she told me she has watched me and heard me do it over twenty times in the last month. I confessed.
I told her ok and I started stroking it. I spanked the little monkey faster and faster and then blew a huge load all over my chest with a drop landing on the headboard of my bed. She stuck her finger in it and commented how thick and sticky it was. And quick as that, she walked out.
Over the next three years, we masturbated in front of each other at least once a month.
I have had to carry on the tradition ALONE. I now still jack off twice daily. My girlfriend and I now both masturbate all the time. I added it up once and that is over 700 times a year and I am 35 now. That is over 15,000 times in my life I have jacked off. That is a lot of bodily fluid....