In the middle of the night is when I think of a lot of things.
I don't think that's unusual, it can be quite a peculiar time.
So I was thinking about the infinite amount of monkeys typing on an infinite amount of typewriters, that sort of thing, and those story-wheel things and random sentence constructors that I used to piss about with when I was learning BASIC programming. For some reason I then wondered if you could take a well-known passage from something, then randomise certain words and see if it would still be recognisable from the original.
My instinct is that it wouldn't take many substitutions before the passage became unrecognisable gibberish, no more than four or five substitutions, something like that. Bet someone's done some work on this. Can't be arsed looking it up now.