http://filmdrunk.uproxx.com/wp-content/uploads/2009/01/willsmithscientology.jpg Thought this was rather clever/funny.
I rather like the Sickapedia version of the defination of Scientology which goes something along the lines of "Scientology is the belief that 2 giant lizards (turtles) brought to earth a spaceship containing 2 aliens which they landed on an island in the middle of the ocean. before the turtles went to the bottom of the ocean to hide in a cave. the aliens crashed and are awaiting rescue in the near future" But as the person then continued "However if you add two italian plumbers and a dinosaur to that you've got the first 4 levels of Super Mario Brothers"
LRH= L Ron Hubbard, founder of said cult. Xenu is the supposed god-figure or some equivalent I think. Not quite sure what OTIII really is but Google does. Oh, and it was pretty darn funny!
OTIII is operating thetan level three. It's like a rank and shows your heirarchy in the organisation.
Wiki has this to say about OTIII to be honest the only thing that it's missing are the words "Once upon a time in a land of make belief unicorns, fairys, aliens and pixies used to play until one day Xenu had an idea etc etc"