It is a well known fact, in households that own a cat, that when there is a box, your cat will, at some time, be in that box:

It has taken me a while to get around to perfecting this fold – it is designed for a larger sheet but I managed to achieve it on a 17.5cm square.

I cheated a little, by crumpling a previous attempt to make the lump for the body, but I think it benefits for  looking more complete.