When we were younger, one summer our family took a weekend vacation to a campground with cabins, and we had our own while our parents had their own.
It was extremely hot that weekend, and after the day was over and we were about to go to bed, our mother told us that it was way to hot in the cabins and that we should probably sleep naked to try and stay cool. We didn't have a problem with that since we had seen each other naked plenty of times before. After she left, we pulled the blinds down, stripped off our clothes and got into our bed. We probably laid there for an hour or so talking, when my sister said she really needed to pee. Since she said it, then I needed to, so I told her I would go with her. When we got up, she started giggling and when I asked her what was funny, she said she thought it would be fun to go to the shower building while we were still naked. She had always been a daring type of person, and since it was almost pitch black outside, I said ok.
We slipped on our flip flops and checked outside, and no one was around so we walked out, bare as can be. It was the first time I had ever been naked outside, but it was so relaxing and free feeling. I LOVED IT. Eventually we made it to the bathrooms, and both went in to go pee. When we were coming out of the stalls though, another girl walked in who looked a little older than us. We all stopped dead and I panicked a little, but my sister as outgoing as she is, started up a conversation with her, acting like nothing was wrong. The other girl was obviously shocked that she was standing in front of two naked girls, but even when she went into a stall, my sister kept talking, asking where she lived, how old she was, etc. The whole time she kept looking over at me smiling, and I had to keep my mouth covered to stop from laughing. Eventually the other girl left, and when it was clear we both laughed and she told me how wet that got her. I felt myself and I was soaked too. She asked me if I wanted to masturbate and I just smiled and nodded my head. I asked her the same and she said she needed to cum bad, so we hurried back and barely got the door closed before we dove into bed and started rubbing our itchy pussies. I came in no time and had two more orgasms before I rolled over and passed out.
The next morning our mom came in and woke us up, still laying on top of the sheets. Before she left though, she glanced down and asked me why I was wearing my flip flops. I was so into my masturbating that I forgot to take them off. I didn't know what to say, so I told her the carpet was kind of rough and bothered my feet. I don't think she bought it, but she said ok and left us alone. The door closed and we both started laughing again. We both sat up and started talking, mostly about masturbation and how often we did it. We both did it about once a day, sometimes more. We kept talking while we got dressed, and after that the day went on. After the vacation we did masturbate a few times together before she went to college, and I love my sister for being so open with me about it.