I remember the day distinctly, down to the small details. I was walking through the carpeted hallway by my sister's room and glanced in as I walked by. I was stopped dead in my tracks at what I saw. Not even five feet away from me, was my sister moving up and down against the edge of her bed. Her hands were holding herself up and her feet and legs were pushing herself up and down. At first I wasn't sure what she was doing, so I stood there studying the scene. She was wearing a small t-shirt and her white cotton panties with pink and green flowers on them were all scrunched up in the crease of her ass, and probably the front too. It came to me quickly what she was doing when I heard her let out a small moan, and heard her breathing heavily. She was getting off! At this point, I didn't even realize girls did this, and thinking of it now, it was probably before she figured out to use her fingers.
I was amazed as I stood there staring, and just the thought of her masturbating made the my blood start to flow. I wasn't getting turned on by her, more the act, and seeing that girls did it too. I don't know how long it lasted, but I could tell she was feeling good. She started to grind against the edge of the mattress faster and faster. And with each thrust, she let out a whimper. I could see the muscles in her legs tense up with each push as her panties disappeared even further, as more of her butt cheeks stuck out. I could tell she was getting closer to a climax because she was moving fast and breathing heavily. She suddenly held her breath for a second and her legs shot straight out. I could see the cheeks of her ass clenching with each contractions of the amazing orgasm she was having, as the rest of her body twitched from head to toe.
My jaw was probably on the ground by this point. She laid forward on her bed catching her breath and her legs parted, and for a quick glance I saw her wet panties. I retreated to my room where I shut the door, pulled my cock out of my shorts and in three strokes was shooting cum onto the carpet.
That night when I went in the bathroom to take a shower, I noticed the same pair of panties she was wearing when she got off on her bed, were laying on the bathroom floor bunched up with her other clothes. She left her clothes laying in there all the time, and I never took notice of them before. But I was intrigued, I remember wondering if girls cum'd like guys did. I instantly was hard as I picked them up to study them. The crotch of the panties was wet like she had peed herself. I brought them up to my nose and remember the salty sweet smell of them. I was so turned on I kicked my boxers off, positioned the panties right over the tip of my cock and rubbed up and down with them. I remember the electricity of the feeling of those soft damp panties rubbing against my cock, and the thought that there had been an orgasm in them just an hour or so before. In about 5 pumps, I pulled them tight as my orgasm released my cum. I could see the cum seeping through the material of the panties mixing with her cum. I had many more sessions thinking of that day, and noticed a lot more wet panties on the bathroom floor!
I don't think she saw me or heard me watching that day, but all growing up, she had a problem with not shutting her door!!