A.H.
It's funny. I have sent this piece of advice to so many people this past month. This really works, I promise. Give him a balloon or party favor that you have to blow with a little force. The blowing forces them to use the same muscles they would use to push when they poop. He'll poop and won't even realize he's doing it. This was a trick told to me by a parent that got it from a psychiatrist that specializes in this particular matter. I've done it several times(I'm a pre-school teacher) and it makes the whole issue fun, easy and a lot less stressful! Good luck.