Growing up I only lived a few blocks from my aunt and uncle's house. They have a daughter my age and as kids we played together all the time. I remember at an early age, maybe 7 or 8 we used to go into the garage and play 'show me yours and I'll show you mine.' We would pull our pants down for each other to look at.
By about age 12 we experimented with kissing each other in secret hiding places. It was all lots of fun. One day when we were 15 we again got into the kissing fun when nobody else was home. This time it was different though. She had developed a body with breasts and I had already been masturbating a few years, as she had too. I remember how passionate that kissing was to this day. In no time we were feeling each other off as we kissed. She was groping my hard tube and I was feeling her tits under her shirt and bra.
I said 'remember how we played that show me yours and I'll show mine' game when we were little? Let's do that again.' It didn't take much encouragement on my part, and I was looking at her nice young breasts and nipples, and her neat mound of pubic hair. She was looking at my 15 year old hard-on. She let me suck her nipples and finger her pussy as she gripped my dick and stroked it. Most of the time we were kissing as we did this. We knew we had several hours and we were totally naked and in bed together.
I wanted to marry my cousin I was so in heat over her. I whispered in her ear that I wanted her to jack me off so she did. I laid on my back on the bed and she laid beside me and jacked me until I came. That was the first time she had ever seen a guy cum and that was the first time a girl had ever jacked me off. After wiping up my mess, she let me finger her and kiss her for about 30 more minutes. I didn't know what a clit was then and I doubt she ever came, but we both had a great time. We cleaned up and dressed and were in the living room watching TV innocently when her parents arrived.
We didn't do anything again after that, until we were both 20. Again we fell into making out secretly. This time though we did far more than just manually get each other off. We are close friends to this day, however we never fooled around again after that last episode.