I think this is exactly what it would take for myself to try it.Yeah, great way to get into cock sucking. The MMF I had was like this - I slid into his wife, got my cock nice and wet, then pulled out and offered a hard, throbbing, pussy wet cock inches from his lips, with his wife saying "Go on Baby, I know you want to. It's OK I'm here and I love you. Now suck that cock."
And he did!