Urgh, cat wee on the stairs........

[chocoholic]

My cat has been weeing on the stairs for the last couple of days, I'm guessing because he is too scared to go out after a big scrap. It is foul and I don't know how to stop him.
A litter tray is no good because my DS will hurl it everywhere.
Please help, what can I do?

I know it's horrid but please can someone help me?

a litter tray where ds can't get at it, e.g up on a worktop ?