He laughed and said I never knew she had such big nips. I told him to quiet down. after all she is your sister. He said yeah, and grinned. he finished...pulling his shorts on and we left.We spent the day laughing and riding and eventually were tired and decided to go back to camp. I told them I could get dinner ready if they wanted to ride a few more rides. They agreed and I went back and got dinner ready. I was just taking the chicken off the grill when they walked up. They both looked so. I told him that they were stories about his size and that recently there had been stories about his ability. He was silent. “How can we be so close and you not tell me when you started having sex?” I asked him. Still a long silence and then he asked me, "How could I tell you? You are my sister, am I supposed to just come home one day and tell you how I convinced some girl to give it up," he asked "that's not going to happen." "Why not," I asked --ok, snapped- "every time I am somewhere where. The desk was thumping against the floor and Lucas was moaning loudly. We weren’t even attempting to be quiet. After a few minutes in this position, Lucas squeaked between moans, “I want to… try… a different… position.” I withdrew my bare cock and slapped his ass. He let out a sigh and I lied down on the floor on my back. I told him to ride my thick dick. He squatted just above my cock and slowly slid it into him. I thrusted up and down into him as he simply hovered above me. Eventually I got. ..You release my neck.My body slumps against the wall. My hips are moving on their own. So wet, I am so wet, oh don't you dare stop, don't you fucking dare....Suddenly, I feel your teeth slightly bite on my nipple, tongue flicking at it. Your free hand is pinching my other nipple. My head falls to one side, one big moan causing drool to slide out from under the gag. The sensations are overwhelming. Pain, pleasure, pain, pleasure...like little sharp shocks. This is all I know now. I cannot see,.