Let me begin by saying that my Cousin was one of the FINEST 15 year olds back then, I was 13 at the time.
I went strolling up to my cousin's house one day and discovered that only her and her younger sister were there. They asked if I would like to come in so I said, 'Sure.' We all went and watched a movie on T.V. when out of nowhere my cousin asked if I masturbated. I said I wasn't comfortable with the question because my little cousin AND my older cousin were sitting here. I said, 'I'll answer if you answer.' And my younger cousin said, 'Yes.' Right after I asked it. Then, my older cousin also said yes and they said now it was my turn so I said yes, as I do masturbate almost every night.
By this time I was rock hard and my pants bulged a bit. They looked at me and laughed and said I had a stiffy. I said, 'and you wouldn't have one right now?' They said they were wet and asked if they could touch my bulge. I said alright, if I could feal them as well. So they started poking my penis and I swear I was about to blow my load at the time but I somehow resisted. I said my turn and felt both of them up at the same time. My hard on got even harder and I thought I was going to blow but I still resisted!
My older cousin asked if she could feel it without my pants on and I said only if I could do the same to them. They said alright but I had to go first. I took off my pants and boxers and they both felt my dick. Next thing I know my older cousin was masturbating me while my little cousin was reaching down her panties to masturbate herself. I blew my load within the first minute she was jacking me. It was the BEST ORGASM I EVER HAD. I said it was their turn so they both removed their clothes and were down to their bra and panties. My little cousin was hesitant but my older cousin went for it exposing her NICE C cup tits with her beautiful pink nipples. She then removed her panties to reveal that she was really wet. My younger cousin then removed her garments and they asked me to finger them so I did. My hard on came back so this time my younger cousin jacked me and got me to ejaculate all over her face and hair. They both climaxed around the same time and for a minute I was THE LUCKIEST MAN ALIVE.
My older cousin sat there playing with her nipples and her pussy at the same time. It was the hottest thing I've ever seen. My younger cousin sat there jacking me some more to the point of orgasm and I silently moaned as my older cousin moaned and my younger cousin licked up my cum.
We put our clothes back on because my cousin got a call from my aunt and uncle saying that they would be home in 10 minutes.
We never did do anything like this before, we never really discussed it, but I always see my cousin's naked because they go skinny dipping with me anytime their parents aren't home. They also send me pics of them spreading their clits to show me the inside of their very wet pussies.
That was one of the best days of my life.
I have another story like this only with a non-relative.