I wouldn't be able to not say anything! Especially when it will stink out my kitchen

Do you have any plastic shopping bags? I have a few that I use as bin liners and before or as the nappy gets changed I will offer them one of those to take it home in.
I totally agree about flushing poo down the toilet and do it when we use sposies from time to time but I really don't like getting righteous on my friends. I find that offering the bag to take it home in is enough of a hint