Yep, "don't Panic" is a good one. My personal motto would be closer to "Share and Enjoy", but I havw always loved the theological argument using the babelfish to prove the non-existence of God.
"Now it is such a bizarrely improbable coincidence that anything
so mindboggingly useful could have evolved purely by chance that
some thinkers have chosen to see it as the final and clinching
proof of the non-existence of God.
"The argument goes something like this: `I refuse to prove that I
exist,' says God, `for proof denies faith, and without faith I am
nothing.'
"`But,' says Man, `The Babel fish is a dead giveaway, isn't it?
It could not have evolved by chance. It proves you exist, and so
therefore, by your own arguments, you don't. QED.'
"`Oh dear,' says God, `I hadn't thought of that,' and promptly
vanished in a puff of logic.
"`Oh, that was easy,' says Man, and for an encore goes on to
prove that black is white and gets himself killed on the next
zebra crossing.
