Well tray surfer.
On one of my types it has a cassette toilet which lives behind a door which then swings across the cabin to give some privacy and room for your knees.
One day we felt the usual trim change as someone went down the back to use it.
A minute later a the hostie appeared and announced there was an old lady in the toilet. Yes yes we said we felt the trim change. No look was her reply.
The Door wasn't across the cabin it was in its not being used position.
The space once that door is shut is about 75x75cm across by 1 meter high with just a hole.
And I once did a charter which was due to the wife of a rather famous African leader having to squeeze one out in the cool box in a kingair with the rest of the cabinet watching on. And being a bit of a big girl the Defence General had to help out wiping for her. I managed to cover most of the sports bar in the Gorge and Dragon in Dar Es Salaam when told that by the King Air pilot who was flying it at the time.