Script: You call your son into your room and tell him that you were talking to one of your friends and the subject of "fisting" came up. You were really intrigued by it and wanted to try it out. You know it's wrong, but you don't want to try it out with some stranger and your son is the only man around the house so you want to try it with him. You start to strip and tell him not to be nervous. That he's been in your pussy before, just consider it "going back home". Encourage him to get naked as well, and comment on how much he's grown since you last saw him. You lie down and spread your legs, telling him to just go back where he came from. He starts to slowly work his way in an out, and you start telling him to go faster. After a few minutes of that you cum, and tell him you want to make him feel good as well. You get down and start giving him a blowjob, continuing to talk dirty. You made every part of him, including that cock, he used to suck on your tits and anything else you can think of. And you have him finish in your mouth and tell him you want to do this all the time now.