To start off, me and my sister aren't super close but close enough for this to happen. I am a typical 16 year old guy who maxturbates daily, I'm not very athletic, and don't have a girlfriend. My sister is 15 years old, has nice breasts for her age, and is quite good looking.
I have had thoughts of her sexually before and have had fantasies of her while jerking, but haven't seen her fully nude in many years.
Our family has a really nice hot tub in the back yard and me and my sister often go in it together. Well this day she was wearing a new one piece bathing suit that was black. In this new bathing suit, her breasts seemed bugger than before and were now pushed up against the bathing suit. She was now wet and I could clearly see her breasts inside and could see her tits.
I got very horny and excited ambout this as I haven't seen her breasts this well in a very long time. I could slowly start to see her tits become hard and I figured she was horny too. I had a rock hard boner by now so so it was good that we were in the water so she couldn't see it.
The only think was that she said she wanted to get out and she quickly got out and went inside to get changed. I was kind of dissapointed as I was hoping we could masturbate together. But as she got out I saw how much her bathing suit was tight to her crotch area giving me a good view of her camel toe and her ass. This got me more excited and I decided to go in with her though.
I grabbed my towel and held it in a way to hide my boner. I went in and found her sitting on the couch on top of her towel. I could still see a nice camel toe and her breasts were still showing nicely. I sat down on the couch opposite to her and lifted my knees up to hide my boner. We both seemed awkward but I bravely asked her if she masturbated. She hesitantly said that she does often and I replied saying I do too. We are both now really nervous and awkwardly sitting there.
I said to her 'I dint know about you but I gotto relieve myself now and we both do it so I might as well do it here.' I hesitantly but excitedly pulled down my bathing suit and my then 5 inch rock hard dick with a good bush of pubes popped out. I slowly began tugging on it and slowly stroking it in a way that won't make me cum so soon. I was so excited and horny to be doing this right in front of my sister.
She said she will masturbate too and with that she pulled off her bathing suit revealing very nice breasts with hard tits and then her young and tight pussy with a tiny amount of light pubes. She slowly started rubbing her clit and I could see and hear how wet her pussy was. Because of seeing this, I had a very intense climax and shot many loads of cum on my chest, stomach, hand, couch, and pubic area. I was so excited that I had just jerked off in front of my sister. I saw that her hips were moving quickly now and she was moaning very intensly. She had a very intense orgasm also and actually shot a lot of her cum onto me which was over 5 feet away. Once I saw her orgasm I was rock hard and started to jerk again but she removed my hand and jerked me off within a minute I came again.
I then rubbed her until she had another orgasm. I am glad now that I gave her her first two orgasms of her life. She is now 20 and I am 21 and she recently told me that those were still her most intense orgasms ever. Since then nothing has happened though.