I made someone stop and turn around so I could get a photo of this sign. I suppose there might be people who grew up on flat land with one storey underground buildings and never watched TV (or only watched Road Runner cartoons?), read books or were otherwise exposed to this concept, but wow. Does our gene pool need humans who don't equate falling over cliffs with serious injury or death?
And here's something else on the theme of injury, death and ignorance that made me laugh out loud.