Then I alternated between gently and violently kissed her on the lips. I knelt on my knees and positioned myself over her face and started jerking off...towards her eyes. "What am I doing?" I said out loud. So rather than just jerk off at her, I pried open her mouth with my fingers and inserted my penis all the way in. I started slow at first, rocking back and forth, with my knees on either side of her head and thrusting her with my pelvis. I would knock her Uvula back and forth in the way back. I couldn't stand it any longer. I wanted to see what was going on. I peered into the room as cautiously as I could. I couldn't believe what I saw. My 15-year-old sister was lying on her back on the bed. Her top and bra were up around her neck exposing her tits. Cindy's shorts and panties were bunched around her ankles. Her ankles were hooked over Jerry's shoulders.Jerry was standing beside the bed hunched over my sister. He was humping Cindy with a grim smile on his face. The guy saw me. I started to thrust like some dog eager to come, short fast thrusts with mam bounced back and forth on the bed with every thrustIt had only been a few minutes since we got on the bed but were sticky with perspiration, mam was feeling her tits through her bra and moaning and I was about to comeHer fanny muscles grabbed around my cock. "Maaam, oh Maaam...yes" I cried Her body released about the same time and we orgasmed together. Her tight lips sucked around my cock as my cock exploded, my cock. 'Yes?''You know you said ... when we, um... 'I could guess what he wanted.'You want us to go to bed again?' I asked. Put him out of his misery. Besides, if he wanted to take his old mum to bed and screw her to the sheets, well, that was rather flattering, I thought.He nodded.I smiled. My plan was to addict him to sex, so that he would desperately want Danni again – or Rachel, if she wanted. I intended that he should become so desirous of sex, and feel so unconstrained, that he would grab.