I'll tell ya what, you don't need Poo Dough.
All you need is the card board cylinder from a roll of TP.
Start to tear it at one end. Once you have it torn and unraveled, tear it up in smaller pieces. Soak it in the sink. Form into a little brown Poo.
I made one and left it in the sink at the old pool hall. Then, I went out and told the Mexican manager that someone left something really gross in the sink and he should get rid of it.
He freaked. I laughed.