A long time ago I wrote about secret government telephone numbers, and before that, secret military telephone buttons. I suppose this is becoming a series. To be clear, the "secret" here is a joke, but more charitably I could say that it refers to obscurity rather than any real effort to keep them secret. Actually, today's examples really make this point: they're specifically intended to be well known, but are still pretty obscure in practice. If you've been around for a while, you know how m...