My stepsister was always curious when she was younger. I would always catch her trying to see a glimpse of my body when I got out of the shower wearing a towel. My stepsister is about 5'6' with blonde hair, slender body and nice 36DD breast. We usually got along when we were younger, we would hangout in each other's rooms and talk or watch tv together.
This takes place when she was about 14 and when I was 17. Well one night we were laying in my bed watching tv head to feet just casual when I started to doze off. I think curiosity got the best of this time because she thought I was completely asleep when I felt her hand touch my penis on top of my gym shorts. By the time I opened my eyes I was completely hard.
She noticed I wasn't asleep at that point but didn't care and kept going. Then she pulled my hard on out of my shorts and grabbed it and started stroking up and down. Next she grabbed my hand and put it on her clit and motioned my to start rubbing it. I started playing with her clit as she took her shorts and panties off, then I slid a finger inside up her and rubbed her g-spot with my middle and index fingers while I rubbed her clit with my thumb.
She started bucking her hips in motion with my hand as I started thrusting my hips into her hand. At this point I was ready to blow. She starting stroking me faster as I started rubbing her faster then I came all over her hand and arm and my stomach as she exploded all over my hand and sheets. After it was over we just cleaned up and she went to bed without acknowledging what just happened. It was a great and surprising experience that I'll never forget.