My neice would often come round to my parents after school to wait to be collected by her mum around 7pm. Sometimes I would have to get home to meet Karen as my parents worked into the evening. Most times Karen would lie on the sofa to watch TV, sometimes she would put some cushions on the floor and lie on them.
One afternoon I was sat reading the paper on the sofa and Karen was lying on some cushions on the floor, her skirt had ridden up and gave me a view of her cute bum and panties. Most afternoons I would get a glimpse of her cotton panties. One afternoon as she lay there I noticed she was squirming a little and sort of thrusting into the cushions, she was laying on her hands and I thought she must be masturbating, as I watched her bum flex and panties stretch it gave me a stiffy, she did this for a while until she sort of grunted and then stopped, I guess she brought herself off.