Write a 2000 word story. I am making a donation at a sperm bank. As I walk to the counter I see a well endowed nurse sitting behind it, she had the biggest bust I had ever seen. When I get closer I see that its actually my sister. My sister tells me they only take donations from men with big penises, so she is going to need to check my size. She put her hand down my pants, trying to check my size. She could not tell how big it was with her hand so she kneeled down and pulled my pants down so she could a closer look. She was shocked at my size, it was the biggest she had ever seen, easily reaching past my knees. She told me she had never seen a penis as big as mine before while working at the sperm bank. She handed me multiple cups saying with the size of my testicles I should be able to fill them all. I was a little nervous with my sister staring at my penis and was having a hard time getting it up, my sister said it was normal and that she could fix that, she opened her coat and started shaking her big bare breasts. As I was about to start, my sister stopped me and said that at this sperm bank its the job of the nurse to collet the sample. She told me the best way was to collect it with her mouth and then spit it into the cup.