Back when I was 14, I had some neighbors across the street. The brother was 2 years older than me and the sister was a year younger.
One day I was over to visit them and the next thing I knew they were both naked and encouraging me to get naked. It didn't take long to convince me. As things progressed the brother was jacking off and cumming into a tissue, but the sister (her name was Karen) wanted me to pretend to be an intruder intent on fucking her. So we played that game, but she was such a small girl there was no way to actually do that.
She was the first girl I'd seen naked and my dick was really hard. We played around awhile at pretending I was going to fuck her, but then I just jacked off and camw all over her chest and belly. It was the most intense orgasm I had ever had. I will never forget that day.