Another weekend at my sister's house, her husband was away working as usual. I went to her bedroom to see if she was in the mood but her first reaction was: "Not today". I knew if I waited a bit next to her she would end up changing her mind. I layed down next to her and started to read an erotic catalog, that made me hard so I started jackoff, in no time she turned back to me grabbing and sucking my cock.