Horny Sister

My little sister has just turned 13 and boy what a horny little nymph she is turning into. My parents work late on a Wednesday night and last night when they went I went to my room and spent a while on the net. When I came down to get a drink my sister Alex was in the kitchen also, she had on a t shirt which only came down to her tummy and knickers, as she stood at the sink I was so turned on by her cute ass I got so stiff, she strolled past me and went back to watch TV, I went back upstairs and surfed some porn, my cock was throbbing thinking of my sisters cute ass. A while later mum called to say they would be very late so I went down stairs to tell Alex, half way down I looked into the lounge through the glass door and there was Alex sat up against the sofa, legs up and apart and rubbing away at her panties, I snuck down and watched her from the hall way, just far enough back so she couldnt see and boy, what a show! She had a DVD on with a sex scene and kept re-watching it as she rubbed herself. Her legs were flapping in and out and she was rubbing and poking her little panties, then she reached around and grabbed a cushion from the sofa, lay on it and began to hump down on it, as she was facing the TV I moved closer to watch her cute bum flexing as she shagged herself off with the cushion stuffed between her legs, her puss looked so good as she pushed her hips up and down, I just had to squeeze my cock. Her thrusts got shorter and harder and her panties worked up into her bum, then she got up so I jumped back and a moment later she was lying on the sofa with a cushion jammed between her thighs and humping into it, her hips and thighs rising and falling as she humped away, her movements getting very jerky and then a hand going onto her panties and some fast finger action, eyes shut and a few thrusts later she comes, squeezing her legs shut tightly around the cushion.

From then on each Wednesday night I wait till mum and dad are out and then wait until I am treated to my sisters masturbation ritual and I end up creaming my boxers. A few times I have taken her soiled panties in the morning and squirted into them.