Placards are not near as bas as now. Just go look at a ladder. Now placards are to thwart suits from stupid people. Everyone remembers the "hot coffee" suit. lol
some of the signs say "alt f4 for nukes" and something like "whine meter".
As you can see, everyone has an answer. Just not one for your question
I like this one. Found on the left side of the gunsight mount in the P51B. "Expendable youthFighting for possesion.Having controlOur principle obsession.Rivalry and retribution.Death! The only solution."