I've tried asking him why but he'll wait for pants to be put on and then sneak off somewhere to dump in them and then come and tell me. He did manage a poo once and I really heaped on the praise but that was ages ago. He's 3.4 and it's a nightmare going out. He wees in the loo standing up but only if I take him as he rarely tells me he needs. More often or not he just pisses himself.
Amazingly he is dry during the night though.