Ha ha, I got a good laugh at a painted sign that was shown in The Colditz Story. It was in four languages: Polish, French, English and German.
Im Deutsch:
Es ist Verboten mit Gefangenen in Einzelhaft zu sprechen.
Translation:
It is forbidden to speak to prisoners in solitary confinement.
Reminds me of the old days when I used to be a Correctional Officer.