I had been visiting a friend and had planned on staying all afternoon but his parents came back and got into a big row with him so I beat a hasty retreat. The weather was glorious so I decided to walk the mile or so back to our house. Dad and mum were away for the weekend leaving my sister Karen in the house. She was in her bedroom doing her homework when I had left earlier on: I had seen her looking out of the upstairs window. I turned into our driveway and walked round the back of the house toward the family room. I caught a glimpse of something white behind the partly drawn curtains. "Hmm, what's going on here?" I wondered and sneaked up to peer into the side of the room.
My sister was sitting on the sofa facing the TV set and was dressed in her favourite oversized T-shirt that showed off her tanned legs. The T-shirt had rode up and I could see nearly all her legs . I could feel my cock starting to throb in my shorts: seeing my sister's body without her knowing it was making me horny. She had nicely shaped 34" breasts (I know this because I'm always looking at them when she sunbathes), dark curly hair that reaches her shoulders and a firm rounded ass which always turned me on. I always had a little peek at her body when she was out in the sun thinking what it must look like naked. One time she noticed me looking at her bikini bottoms and the way the material had started to pull around her cunt defining the sex inside.
"What are you looking at, perv?" she had snapped and turned over onto her front. Now I could see the T shirt had risen to reveal a brilliant white pair of panties that contrasted with the rest of her tanned skin. She stretched out her arms and pulled off the T shirt.
"Wow, what a gorgeous pair of breasts," I thought - full, firm, and suntanned with the pinkish brown aureole small and neat around her rubbery nipples. She slumped back onto the plush sofa. She had obviously sneaked into my room and found one of my adult movies and brought it down to view, thinking I would be away all afternoon.
My eyes fell to her torso and followed the beautiful firm flat stomach I had admired so much in her bikini. She idly pulled on a brown nipple and it began to thicken and grow, standing erect from the breast.
Being a voyeur had turned my cock into an iron rod: it had never felt so hard as this.
She clearly was about to play with herself in earnest and it would only be a matter of time before she would be stroking herself. "Time to confront sis," I thought, and marched around the corner and into the room. "What are you up to then, Karen?" I said.
She leapt into the air and tried to cover herself up. "You bastard," she shouted, "you were spying on me!"
"I wonder what mum and dad will say if I tell them what you were doing." She looked worried. "Hey, don't worry I get turned on by porno films too, you know. There's nothing to be ashamed of, Karen," I said in a matter of fact way.
"You won't tell mum then?"
I ignored her question. "Mind if I join you, sis? After all, it is my movie you are watching!" I sat in the chair opposite her before she could object and began to watch the film. She kept her hands across her breasts but this allowed me a good look at her cunt: it sure looked full and plump under her panties. I made several jokey comments about the size of the actor's cock. She laughed nervously and slowly began to relax.
We carried on watching and after a while I noticed that her face had a dreamy look to it and she had begun stroking her nipples, forgetting I was there. I pretended to look at the film but couldn't tear my eyes away from her body. "I think I'm going to have to join you," I said casually.
"Whatever," she said her eyes glued to the screen. I lifted my hips and slid down my shorts: my cock sprang free and slapped against my stomach. I noticed that the purple head was exposed and straining. She glanced over at the sound and sucked in her breath. "Jeez what is that? It's huge!" she exclaimed. Her eyes were riveted on my cock and I decided to give her a bit of a show pretending to ignore her. I lifted it up to its full height and slowly pulled the foreskin down so the large purple head was fully exposed. I dipped my finger in the pre-cum that was oozing from the eye and rubbed round the head to lubricate it. I slid the skin slowly up and down letting her see my cock throb each time. She continued to stare and bit her lower lip watching my fist skimming up and down my cock.
"Come on sis, let's see yours then," I said. Fixing her eyes on my cock she slid down her own shorts to the ankles. It was my turn to gasp: she had a thick mass of curly brown hair atop a prominent bulge which lifted away from her hips and seemed to shout out "look at my sex!". Her sex lips were a darker colour from her body and protruded slightly between her bush and were already shiny with her excitement.
I began to pull on my aching cock all the time looking at Karen's expression. I stood up and moved directly into her line of sight. Her eyes fell onto my hand as I slid my foreskin up and down my stiff cock. She stared at my cock all the time moving her fingers round and round at the peak of her cunt.
