Write a story about the following. I am making a donation at a sperm bank. As I walk to the counter I see a well endowed nurse sitting behind it. When I get closer I see that its actually my sister. I told her I had an interesting way of giving my donation. I bent her over the counter and pulled her panties down and then I shoved my massive cock into her pussy. I pounded her doggy style for several hours. When I was done I picked her up and carried her to the entrance of the building, I bent her over and told everyone that this is how the nurses are taking donations now. I walked over to a nearby bench and watched as her pussy was pounded.