My grandparents on my dad's side, who passed away before I was born, were very liberal. My dad and his two sisters grew up as nudists, and he told me that sex and masturbation was always talked about at home. My dad said he masturbated with his sisters.
So, I grew up in a similar environment, since my mom is also a nudist. Both of my dad's sisters are married, and they each have one son. They are both younger than me, and also grew up as nudists. It was I who taught them to masturbate.
Almost every month, the whole family travels to my parents' house in the mountains. Its a huge house, with eight rooms, a huge pool, and a lake within our territory. On sunny days, we have a BBQ down by the lake, staying the entire day naked, playing soccer and swimming naked.
My two cousins and I have masturbated together ever since I was 13, and they 11 and 10. All our parents know we masturbate together. When in the house, we go to one of the rooms that isn't being used, and have a jerking session that lasts the whole night. Sometimes, my mom would come in and give us a hand. I don't think any of the other grown-ups know she does this.
Anyway, one weekend, after a long sunny day of playing and jerking at the lake and pool, we went to bed. Well, actually, the three of us went to the room we use to have another session. We then heard a knock on the door. We all said 'Come in', since it was no big deal what we were doing. Then the door opened and one of my aunts came in, and saw us three naked on the bed. One of my cousins (Tom) was jerking us off, while the other one (Andrew) was jerking Tom. I was just playing with my nipples as I enjoyed the intense pleasure.
My aunt then came in, and said that while her husband was showering, she wanted to have a little fun before she had fun with her husband.
She was wearing only a red nightgown, with long and wavy black hair down to the middlle of her back, and a pair of E cup breasts. They were amazing! I always got hard when I saw her.
She came onto the bed, and got naked. She knew we were all staring at her boobs, and said: 'They are nice, aren't they? Who wants to play with them first?' I instantly volunteered, as Tom and Andrew continued to jerk each other off while they saw me suck and squeeze my aunt's boobs as she jerked me off.
I was about to cum, so I switched places with Andrew. Tom and I kept masturbating each other, watching as my aunt now placed her boobs around his dick, and moved them up and down. Later on, Tom, her son, did the same thing.
Then, Andrew (the smallest one) and I wanted to tit-fuck her. I sat on top facing her, and Andrew sat between her boobs and her face, facing me. My aunt's breasts were so huge, that we could fit the two of our hard cocks between them. As we did this, our aunt held Tom's dick in our direction, and wanked him off. Then, Andrew and I came between her tits, also cumming on each other, as Tom then squirted his semen onto us and her boobs.
It was the best orgasm I ever had!! She then said someone had to clean her up, and the three of us instantly volunteered, and began to lick her tits clean. After she left, the three of us lay down on the huge bed, naked, and fell asleep. We did, however, wake up twice during the night to have some fun.