Completely random thought which doesn't fit anywhere else. In the Hitchhiker's Guide To The Galaxy series, I have a theory that Marvin knew what the great question of life, the universe and everything was, and what's more, he even mentions it in (rather fittingly) "Life, The Universe and Everything".
“You may not instantly see why I bring the subject up, but that is because my mind works so phenomenally fast, and I am at a rough estimate thirty billion times more intelligent than you. Let me give you an example. Think of a number, any number.”
“Er, five,” said the mattress.
“Wrong,” said Marvin. “You see?”
The question is "Think of a number, any number". We all know the answer is 42, so the mattress's answer of 5 is, as Marvin points out, wrong.
Marvin knew, but he never told anyone because nobody ever asked.