Denise was wearing a strap on device with a long slender flesh colored cock. She was rubbing large amounts of lubricant on it. "Get on the bed on all ...ours." She looked so serious and the calm cool way she said it gave me a shiver down my spine. I began to wonder if she knew about my sexuality. Instead of questioning, I just did it. Denise stood at the edge of the bed and had me scoot back into position. She stuffed two fingers with lube up inside my hole. Denise wasn't gentle as she worked. I threw both arms around her, and started thrusting as hard as I could, trying to make it really last for her.I knew my own was approaching, and I tried to muffle my moans against her neck, as I shot glob after glob of my seed into her sucking pussy."Damn," she said as we caught our breaths and started getting dressed, "remind me never to go longer than a couple days without you again!" She gave me a quick peck on the lips, and then said, "I think I may be a little sore tomorrow, but it was. " Billy said. Cheryl was hoping he would say this as her pussy was getting really excited the longer this went on and the thought of watching her young, handsome son masturbate and shoot his cum out really excited her. "Ok Billy" she said, "that probably would be a good idea. But let's hurry ok. I don't want the Dr. or nurse to suspect anything." Billy then reached for his shaft and began to stroke his cock. Cheryl, holding a tissue in readiness to catch her son's load, watched very intensely. “Christ, you’re obvious. Standing there waiting to see what she looks like in a bathing suit. Sit down and behave.”“Sis, I love you. I wish I’d had time to give you a good going over when we got home, but right now, I’m totally strung out. I can’t wait to see what she looks like.”“Well, he’s no Frankenstein, you know. I want to see him, too. But let’s try to be, you know, cool about it. And,” she added, “if you’d tried to do me this afternoon, you’d still be cleaning up. But, anytime you want.