We had the same problem too - the pps have had some great suggestions! But I will say it does happen, just takes longer. DS now has all the poos in the toilet at home, but we have yet to conquer this at someone else's place. This is our final hurdle. It's taken a couple of months of undie cleaning though. I basically said "yucky" to poo, and we talked about how it didn't feel nice.

I have heard that the poo drop in the toilet can be scary, I was about to buy a potty to try pooing on that - you could have him choose one, or choose a special seat for the toilet. I've also heard people talk about the poo wanting to go in the toilet to have a party with the other poos (yes, lol). DS quite liked that concept. The sticker chart worked wonders for us though. We went and bought a piece of card and some stickers - he chose it all (duck stickers). I hung it in the toilet and he wanted a duck. I said "they're for when you do a poo in the toilet". Then DH brought some chocolate home (like the little round ones in a stick - does that make sense? So he gets like one square at a time) for when he does poo in the toilet. So he got very excited about ducks and chocolate. The ducks are gone now, but the chocolate remains until it's all gone. I am putting some in the nappy bag for when we go to other people's houses though!

So I'm not above bribery. Or do we call it rewards, lol.

And your world becomes about the toilet - but try not to pass that on to your DS, they do tend to become obsessed too!