I took the video player up to my room and hooked it up to the TV. Then I settled down to an hour of private pleasure. The video left nothing to the imagination. A pretty young girl, about the same age as Allie with a man old enough to be her father who was trying to persuade her to take off her panties. She appeared reluctant, shaking her head and retreating away from his reaching hands. Then he grabbed her and she was left with no choice as he tore her flimsy panties from her slim body and pushed her to the floor. She shook her head as he forced her slim legs apart and positioned his erect cock between her thighs.

My own prick was rigid with excitement and I was stroking it through the material of my jeans. I'd just reached for my zip when I heard a faint sound behind me. I turned quickly to see my little sister, my innocent baby sister staring entranced at the action on the screen. I grabbed for the remote and stopped the tape but it was too late.

"Wow! Where did you get that from," she said, without a trace of embarrassment.

"Mind your own business. It's not for little girls," I said trying to hide my embarrassment at nearly getting caught with my cock in my hand.

"I'm as old as she is," she pouted, pointing at the screen. "If she can be in the video, why can't I watch it?"

"Because she isn't my little sister - anyway I didn't invite you. You're supposed to knock, remember?"

"I did knock. You were just too excited by your dirty video to hear me."

"I was not excited," I said blushing hotly. "You must have knocked very quietly and I didn't say you could come in anyway."

"You looked excited, the way you were stroking yourself."

I looked at her in embarrassed astonishment but she didn't look the least bit concerned.

"What do you want?" I asked resignedly.

"I want to see the rest of it," she complained. "Let me stay and watch it with you."

"Not a chance - you're too young," I told her firmly.

"I bet mum doesn't know you're watching stuff like this. Or that you play with yourself," she added virtuously.

I stared at her innocent face and wide open eyes, trying to decide if she was threatening me.

"Don't worry - I won't tell her," she said softly. "But please let me watch it with you. I don't mind if you want to play with yourself."

The thought of my little sister watching a sex video with me was quite exciting. She was only ten but she was pretty and petite, a cute kid with enormous eyes that captivated everyone. I was still horny as hell and I couldn't stop my eyes wandering down to the outline of her baby tits pushing against the thin cotton of her T-shirt. They were still only the size of apples but they looked bigger because she was so tiny - the top of her head only came up to my chest. Although she still pretty much looked like a little girl, she suddenly looked very sexy. Her little nipples thrust against the material and I could tell she wasn't wearing a bra.

She was more attractive than the girl in the video. I had never thought of my sister in a sexual way before, but I suddenly realised that she was almost a woman now that her body was starting to take shape and the idea of jerking off while she was in the same room suddenly excited me. I knew that I had to convince her that it was me doing her a favour or she'd have something to hold over me for life.

Finally, I said, "Okay you can watch it with me but you have to do what I tell you to do."

"What does that mean?" she asked suspiciously.

"What ever I say... Okay?"

"Okay but as long as you don't do anything to me."

"Don't be silly, What could I want to do with a ten year old kid," I said sniffily.

She looked offended but her eagerness to see the video overcame any objections.

"Okay," she sighed, "What do I have to do?"