My husband wee'ed on a chair a couple of times -- I thought that the shape (seat, as in toilet and back of chair, as in cistern) was the explanation. And after all, one sits on both toilet and chair, so I could see the connection.
Didn't make cleaning the woven rush seat any easier though......
My dad when he was still at home with advancing dementia, would wee against radiators -- possibly mistaking the white panel for a public urinal?
Or am I being too charitable?
It would be funny if it wasn't so sad. Bless you all.xxxxx