moomin, I'm with you on "poo" personally I prefer shit, or even shite, slightly more refined. My mother always called it business, that doesn't seem to be used in a number 2 sort of context anymore. Number twos is a nice euphemism in my opinion, but others may find it coy, it is of course, but it's quite a good way of referring to the opening of one's bowels to children, poo is the stuff in babies nappies!
Describing one's stomach as a tummy as an adult is almost in the same category as referring to your mother as mummy, sounds as if the speaker has never left their childhood behind.
Can anything better the Australian term "rack off" or the Irish "feck off" We all know what they mean but they have a much more folksy tone!
My number one ridiculous euphemism would have to go to the Americans, yes them again, in the use of the word "restroom" instead of lavatory or toilet. We all know what they are there for and aint for having a rest!