S.A.
My mother had some problems with my second brother doing the same thing. He decided out of the blue that he didn't want to stop what he was doing to go poop on the potty. It took to long I suppose. He didn't like to clean himself either. He would just gag and gag.
Finally my mom got so sick of it she told him she would no longer clean him up if he went in his pants. She would take his pants off and make him clean himself up as best he could with toilet paper making sure he flushed so as not to overflow the toilet and then she would make him get in the tub to finish cleaning himself. She would tell him how gross it was to poop in his pants and if he went on the potty it wasn't nearly as bad and she would help him clean up....but only if he went on the potty.
For some reason he stopped after the first time he had to clean himself up. Guess he figured that was more disgusting than sitting on the toilet and cleaning himself there.
He was a silly bird and would literally gag when he smelled his own poop.
You should have seen him changing diapers as a dad. TOOOO FUNNY!!!!