LOL!!! your not alone!! my son had a poo fetish not too long ago, he used to dig in his diaper and pull out poo and play with it, I was mortified!! But one day it just all stopped, partly because I put him in a snap t-shirt to keep him from having easy access to his diaper. I also used to tell him NO NO!! very loud everytime he did it, it at least got his attention and he stopped. Maybe he just needs to be more supervised when doing his duty for a while, just until he stops doing it.

Good luck to you.