TOPIC: Odd warning label and outlet

I found these two odd things at two different houses.

The warning label was up where a light switch would be but it didn't operate anything nor was there anything below it. Any ideas what they were trying to warn someone of?

The outlet is just weird to me. First time I've seen one. What would have been plugged into that?

Bottom plug pic is a combo tandem and parallel outlet is now at least 60 years old. In most cases they are over 100 years old.  The wiring behind the wall would then have to be cloth knob and tube un-grounded wiring.