A long time ago I got a nice thick 8" dildo and I used it to try and get my wife to do MMF threesomes. I would dildo her pussy while she sucked my cock, or a small dildo in her ass big one in her pussy. I would talk to her about two guys doing her. She would always say no but I could tell it really turned her on. She said she doesn't masterbate, but I caught her one time and grabbed my old camera. Needless to say my training worked and she has had over 50 MMF threesomes.