I guess the theory behind it Fletch would be that you could use the word or sound -before- he goes for his nap, so he's done his poo before sleeping? I'm not sure I'd like to have word association with going to the loo.. you'd only have to say the word in conversation, and your kid will need to go! hehe.

I do know that when I was little, altho I think this was after being toilet trained, that mum always sat me on the loo before going to bed and MADE me go. Running the bathroom tap usually helped too. Even now, it's my habit to go to the loo before bed, even if I'd only gone 10mins before, I just HAVE to go before bed. LOL.