DOG/TROUSERS

There's a pair of trousers lying abandoned on the grass outside the window, sprawled and twisted. Whenever I stick my head out there to smoke, I see them as a small black dog squatting to shit, it's tail waving like a cheerful flag; then it resolves itself back into lost trousers. Like the famed duck/rabbit of Wittgenstein, Gombrich et al, I can see either trousers/shitting dog - but not both at the same time.