GS-108 When my family wasn't home, my sister's friend came to visit and it was just the two of us. While I was waiting for my sister to come home, I changed into bloomers and crawled on my hands and knees, saying, ``It's more comfortable.'' I got excited by the bloomers that penetrated her, and when I rubbed her dick, she said, ``You can have sex with me,'' and my sister's friend, who was eager to have sex with me from the beginning, came!