I first read this in 2001 on an outhouse door while treking in Tasmania:

ODE TO THE WOMBAT

As you pound along the track

Eyes wide open and ears pinned back

You may have noticed those queer square turds

And thought, if not expressed in words,

The pain of such defecation

Baffles the imagination.

But it ain't done to entertain us—

The wombat has an oblong anus.

So if at night you hear pained cries

Outside your tent, feel no surprise.

With eyes shut tight, teeth clenched with pain,

A wombat's gone and crapped again!