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 digging into her and when I rubbed her dick, my sister's friend, who was so motivated from the beginning, said, "You can have sex with me!"