I could hear a noise down the hall and went to investigate. I sneaked to the door of my sisters room and slowly pushed it open and there she was. Bent...over her desk with her panties at her ankles and some guy in his forties fucking her from behind. My dick instantly got rock hard as I stood there in amazement. I had never noticed before but my sister was so fucking hot. She had long athletic legs and a tight perky ass that went along well with her amazing toned body and small-ish perky tits.. I drank the rest of the Labbats beer I was drinking as Cathy took my cock in her mouth and began to slurp and suck my cock. I put my beer bottle down and grabbed her by the hair and began to pump my cock in and out of her mouth to the rhythm of the couple on the bed fucking. I couldn't help notice her eyes as I fucked her mouth and how willing she was to be handled so rough by me. As I felt my balls tingle and tighten, I held her mouth down on my cock as I erupted in her throat. I pulled Cathy. “Bed-hog.” Clutching the sheet that she had stolen at some point during the late hours, she sat upright and looked around the bed. Taking in Marcus, who had pulled the ratty comforter up to cover his legs, she laughed. The sound brought warmth into his chilled body. Untangling the sheet, she covered up Marcus so that he could warm up and stay comfortable. “Sorry about that, I don’t share well with others.” Marcus sat up a little and leaned on his elbows facing Hadley. “You don’t have to. Meanwhile, Jim and I chatted about work and sports and other manly subjects, while his son climbed all over him. His daughter, the artist, quietly amused herself with a coloring book and a box of Crayons. Katy's husband and I had always gotten along well. Despite my complete and utter jealousy, I did consider him to be as close to being as worthy of Katy as any man could be (except for me, of course). Our conversation was interrupted by the telltale tinkle of ice cubes clinking against the.