I guess I'm a voyuer. I just love watching my wife's sister having sex. It started when I heard her in the next bedroom enjoying early morning sex with her boyfriend. I had always thought she was dull and dreaded her coming to stay with us. So I just couldn't believe it was quiet Anna in the next room last month, telling her boyfriend what to do to her. Telling him to take her knickers off, and just how to lick her between the legs. It was detailed and obviously the advice of an expert. I just couldn't square the sounds coming through the wall with the shy girl I thought I knew. I could hear her telling him to "suck on it, suck on it". Our walls are not very well constructed, so I could here every move of the bed and even the sound of him kissing her down there. Ever since I've been obsessed with actually seeing them in the act......