Being a lusty girl, I was fascinated by her defenseless ass and wanted to do it without even looking at her face. So I immediately put my penis in her and started thrusting hard, cumming inside her vagina as if she was just a hole for my sexual satisfaction. I thought it felt good, but the hole I thought was hers was actually her sister, so it was a disaster! I was in a desperate situation, but she said, "I'll do it without telling you, so please do more..."