Good idea because it gave me another one. How about that the couple is wealthy and they advertising in magazines to find a third partner. However non of them who came to them is good enough for them. Most of them left the house when they bring up the bondage topic. Because they want that kind of game.<br/><br/>But they got a maid who is usually sent away when the candidates arrive. But one night she mess up something and she heard them what are they talking about. Then offer herself or they find out she was eavesdropping so they have a little chat with her. Or one they the husband or the wife think about their young maid.