Dilbert comes down to the caves where trolls (accountants) reside and gets a tour. The guide points to a troll sitting behind a desk, and mumbling in a stupor: "nine, nine, nine...".
Guide: And this is our random numbers generator.
Dilbert: Are you sure those are random?
Guide: That's the problem with randomness - you can never be sure.
Edit: Found it here: https://www.americanscientist.org/article/the-quest-for-rand....
And thank you, Scott - many laughs thanks to you.