Man, I haven't seen that in a LONG time!!
...
Sean needs one for Odyssey, too!
As long as you mention it, I can tell you precisely the first time I saw this (although it had the word "kontrol" in it, right after "machine":
"Das machine kontrol ist nicht...". It was 1974 (yes, 34 years ago), and it was taped to the front of a PDP-8/e minicomputer for which I had some administrative responsibilities.
Even then, the sign I remember was probably a third- or fourth-generation photocopy of an original that pre-dated it by another decade. But it was funny, and, oddly enough, I think it actually worked, which is to say, it had some effect in keeping people's paws off the controls.
Ah, the good old days.
-Sean
http://OurOdyssey.BlogSpot.com