I heard the front door open and then closed as my father and nineteen year old sister went out. Him to work and her to college. My mother worked from home and I went to college a bit later in the day...but not today...oh no, today was Friday. Today was mom and son day. I walked down the stairs and my mother was all ready. Stark naked, even at 45 years old she had the breasts of a college girl and a body of a triathlon. I slipped off my pants and shirt and took my mother around the waist. I was already half a foot taller than she was and a lot stronger. I pulled her close and our lips met. Tongues twisted and saliva; sweet and warm mixed. With a single hand she led me to the futon and sat me down.
"Arms up." She said. I lifted my arms up and she tied them together with some nylon rope and fastened my arms to the lower rung of the futon bar. It was different, normally I was tying her up but I didn't mind a little switching from time to time. She quickly bound a thick black blind fold around my eyes and tied it tight. The room fell silent as she moved around me. It was a great deal of time before I felt soft fingers on my chest. I shivered with pleasure as the tips of those fingers traced their way down to my groin and up my cock. With each pulse it stiffened to stand erect. Gentle hands wrapped around my cock twisting as they worked my cock up and down slowly at first and then harder. Then her mouth wrapped around my cock. I had experienced my mother's mouth a dozen times but this...this wasn't her mouth. My mother would lick my cock from stem to stern; tip to balls but this was different.
"Mom?" I asked through heavy breaths.
With a quick pull the blind fold came free and I found, not my mother but my sister was sucking at my cock. My mother stood across the room with my-
"Dad!" I said shocked and embarrassed. I struggled against the rope but it wouldn't budge.
"Well hey son!" My dad laughed. "Relax son. I know about it all but you don't know that your sister and I have been doing it too. About time we do it as a family."
"Cum slut wife! Come here!" Dad shouted. I watched my mom fall to her knees. "Yes master." He grabbed her by the hair and she opened her mouth wide and he pushed his cock into her throat. I heard mom gag on his cock. Loud squishing sounds and gurgling as his cock clogged her throat. He pulled her head all the way so that her lips were flush with his skin. Her eye bulged and face darkened and I could've swore my mom would pass out but then he let her go and she gasped for air coughing and drooling long streams of cum and saliva. I looked down at my sister who was slurping at my cock though she wasn't taking all of it in and with my hands tied I couldn't make her. She would suck delicately on my head and swirl her tongue and then take another inch into her mouth. It was torture.
"Daughter! Come." Our dad said.
"Yes daddy!" My sister said and crawled to him.
