As soon as my sister came home from her boyfriend's place after a long time, she grabbed my hand and said, "Show me your dick!" When I said I couldn't do that, she forced me to take off my clothes and put it in her mouth. My boyfriend told me that I was bad at giving blowjobs, and she was going to use me as a practice dummy. My sister gradually got better as she listened to me. I came with her mouth. After that, she went back to her boyfriend's place, satisfied. A few days later, the sister came back again. She was crying in the bathroom. This time, she stopped halfway through, saying, "H doesn't feel good at all." She watched videos, immersed herself in masturbation... and then in front of me...