It's on the back of all four elephants at the same time (they stand with their back ends together). They've got an animation of it on both of the Discworld DVDs (Wyrd Sisters and Soul Music).
For those of you who aren't familiar with Terry Pratchett, he did to fantasy what Douglas Adams did to SF. One of the most memorable (but not the best quote) comes from one of my favorite books, "Guards Guards!" An existing memeber of the night watch is breaking in a new kid, showing him the ropes:
"The job of the night watch is to walk down the street hollering '9 o'clock and all's well!'."
"But what if all isn't well?"
"Then you bloody well find yourself a different street to walk down!"
(Appologies to Terry if I got the quote wrong).
There are better and more bizzare bits from his books, but that is a quick, easy to remember sample. Other oddities have been the time monks, bonsai mountains, and a butterfly that caused serious winds every time it flapped its wings. It all fits together in a way that is illogically logical and works.
You know, of the several standins Death has had in that series, there's still one character that I'd like to see in that role, someone that quite often knows more than he's letting on. One word, and you'll know who I'm talking about.
OOK.
Not all of the, what, twenty-some odd books are great, it took him a few books to find his groove, and once in a while a book will feel like Terry rushed it, but I highly recommend the whole series to anyone that likes satire.
Well, I've rambled OT enough. Time to go find something to ramble on that's on topic