This is a frivolous question but Im in need of such things.
We've just got our new composting toilet. It will be installed as soon as True-love runs out of reasons to postpone the job. Like "Let's get this gig on Sunday over in case I chop my fingers off with the hole-in-the roof cutter." He's too precise to have called it that but I've forgotten it's correct name.

Oh! It's grand. Looks like you could drive it to town or maybe Jupiter. All shiny and pearly-white with a handle and tubes and a high gleaming seat.
I need to put up a sign about how to treat it when a visitor makes a -- how to say it delicately? -- well I can't you see -- that's the problem. Most of our friends can deal with "poo", "shit", "dump". Our medical friends are used to, "bowel movement", (which I've always thought comical) "faeces". It's the occasional visitor who is genteel and easily shocked, and I don't want to offend, who's the problem. That's when I think about the Queen. When I was a kid, in a working-class suburb of Melbourne, the Queen used to call on people like us. Not often -- she only came to Australia occasionally to see how we were doing. The front page of the paper would show her, drinking tea, with her finger delicately curled around some Mum's best china cup.   It became a standard of some kind. Our mothers said, "(insert something to do with dust, scattered toys, cubby house on the front lawn, dirty faces, or tidiness) and what if the Queen came to tea?"
So you see -- I thought if I could think of a word that would be appropriate for the Queen to see -- I'd be laughing, Bob's your uncle, or no worries.
I believe we should put aside the idea that the Queen has people who would carry out the necessary procedure for her. I'd gladly do it myself. I believe this is irrelevant.
Thank you in advance, Joy