This happened when I was 13 and my sister was 16
I guess I discovered girls the easy way. I had an older sister who one minute I didn't notice and thought she was a jerk, to almost like turning on a light suddenly I noticed everything. The short skirts, the occasional flash of panty and the bikinis. Best was when she would pad around the house in her bra and panties only which she did a lot. I guess she felt comfortable with it. Either that or she enjoyed it. A couple of times when our parents were out, she would walk around the house naked. I didn't enjoy that because I got a hard on and she would tease me about it.
Anyway, one day she had come home from a netball match and there was something about her. She smelled sweaty, but it was a nice kinda smell. Not like stale sweat. Again, our parents were out and she cast off her netball kit in the kitchen while telling me how hard and hot the match had been. Soon she was standing there in just her panties. That's when I noticed something new. There was a different scent, not just sweat, something more, I don't know, more female. She took her panties off and dropped them in the laundry hamper and said she was going to take a shower. I didn't dare move because I was so hard.
When she had gone I went and got the panties. They were actually wet. I don't mean damp, I mean wet. Instinctively I put them to my face and breathed in. My head started to swim and my knees buckled. I had never smelt anything like it. Also, my cock was twitching. Now, at this point I had never masturbated. But now, I took my cock out and held it while smelling this lovely scent. There was sweat, of course, but also something else which I now know to be pussy. There was also a hint of pee too. I guess I had started to rub automatically.
Suddenly I felt something happening. Jet after jet of cum shot out of me and again instinctively, I put Anna's panties there to catch it. I just couldn't stop and it felt wonderful. Right up to when I heard her voice. 'Well, looks like my kid brother has grown up.' I was terrified she was gonna tell. But she didn't. Of course there was a price to pay and that was that she wanted to watch me a couple of times. At the time I guess I had discovered pussy. I feel bad that it was my own sister, but we never touched each other. OK there was some mutual masturbation and I got to see how a girl does it to herself. I also saw Anna squirt a couple times. I went on using her panties with her knowledge for a while. From time to time she would even give me pairs of her friends when she had sleepovers and would even talk to me while I used them. 'Doesn't Claire have a sweet smelling pussy? She has no hair there because she shaves and you can see her pussy lips.' Stuff like that. Thinking about it, I don't know how Anna KNEW Claire had a sweet smelling pussy. But all I know is that the rule was that when Anna brought me someone elses panties I had to cum right in the crotch.
Fooling around like this ended last year when I got my first girlfriend, again, thanks to Anna. She set me up with a girl who was, let's say, a LOT of fun.
Well, that's my initiation into masturbation. I know it was kinda sick, but at the time it just felt great.