Gozer the Traveler. He will come in one of the pre-chosen forms. During the rectification of the Vuldrini, the traveler came as a large and moving Torg! Then, during the third reconciliation of the last of the McKetrick supplicants, they chose a new form for him: that of a giant Slor! Many Shuvs and Zuuls knew what it was to be roasted in the depths of the Slor that day, I can tell you!
-This might very well be my favourite movie quote ever. It is a beauty line of throwaway nonsense spoken with great conviction by Vinz Clortho the Terror Dog, who just happens to be possessing the body of weenie accountant Louis Tully (both marvellously played by Rick Moranis).
What I love about it is that it is not even meant to be understood. It does little to further the plot (beyond the hint at a 'pre-chosen form') and only contributes to the world building in the absolutely loosest sense. You don't loose anything from the movie by not understanding what is being said.
This sort of thing is hard to do in most rpgs ("gimme the Monster Manual! I don't remember the stats for a Slor!"), or in any form without sounding idiotic, but it is marvellous when it works.
On a not completely unrelated note, I'm taking another shot at the Malazan books by Stephen Erickson and Ian Cameron Esslemont.