More Fun With Sister

My sister and I were staying at our grandparents one night and after they went to bed we started fucking for most the night. It was about 330 or 4 in the morning and we were on our sides fucking both facing our grandparents bedroom door when the door all the sudden opened. My dick still in my sister we set there acting like we were sleeping while grandma messed around in the kitchen. After a couple minutes I slowly started moving my dick in and out while actually watching our grandma in the kitchen. Finally she went back to her room and closed the door. I was about to cum my sister spun around sucked me dry and swallowed every bit.