I can say that I and my sister are the opposites, maybe because of it we are also bestfriends. For starters, I like girls and my sister is mad for guys I can say she's a nympho, she's always looking for a guy to fuck. One day, having girls talk I told her that I a had a black friend that has a big cock, not that I've used but he stayed at my place and I've seen it while he was having a bath. She got completely crazy about it and wanted to meet him, so I arranged the meeting at my place and offered my friend has my birthday gift to her.