It was a hot summer in the early 1950’s. With both parents working, my twenty year old sister Mary and I were out of school on summer break. Mary is two years my senior. With no air-conditioning, each afternoon we would seek relief from the heat by talking or reading as we laid on the cool sheets of her bed.
One day, which is etched in my memory forever, as we prepared to do the usual Mary began to take off her blouse and lower her shorts. She was standing there in her thin panties and see through bra. This was such a shock to me as I had spent hours spying to see her naked or at least in some state of undress and here she was! As she disrobed she looked at me and nodded. I assumed she wanted me to follow suite. I stared at the dark triangle of brown hair showing through her thin white panties and the top of her pink areola and erect nipples pressing against the thin top half of her bra.
Pulling down my shorts and tossing my tee shirt to the floor I stood in my white jockey shorts. Turning from her I tried to push my now stiff cock up against my belly. Mary laid down on her stomach and I lay next to her on my back, not daring to move for what seemed like an eternity. I glanced down at her beautifully shaped butt and with a trembling hand, began to lightly stroke and rub her ass cheeks. I was cretin she would make me stop. To my surprise she didn't resist. Was she asleep? Then I heard,
“HmMmmmm...Uhmm.,.” As she ground her crotch into the bed.
Becoming braver I straddled her hips rubbing and massaging her back. My cock strained against my jockeys and nestled between the cheeks of her ample ass. She wiggled against me and my shaft nestled in her crevice. I moved my hands up and down her back. As I went up I slid a hand under her bra’s back strap. After a few repetitions she reached back with out a word and unsnapped the bra freeing her entire back to my touch. Mary then raised slightly and wiggled her bra straps over her shoulders, flinging the bra to the bedroom floor. I continued my massage now including the sides of her 38 C tits. My rod rode between her plump valley with each lung up and down her back. Again I heard,
“Ohh..Mmmmm...mmmmm. Oh.. .ohhh.”
Becoming bolder, on my trip down her back I began to roll down the elastic band topping her panties. Each trip down meant another lowering of the panties and more of her ass cheeks revealed and rubbed. By the time half of her ass crack was exposed she lifted her hips and pushed down one side of her panties while I pulled the other side and dropped them on the floor.