Things I Know I Know

I was driving past a construction area while I was up near Chicago and I saw a big utility vehicle with one of these signs on the back that said:

Don't Follow Into Work Area

And I thought, well, you--the casual driver on the highway--would never follow it into the work area on purpose. You'd only follow it into the work area if you thought it was still the highway--if it was dark or rainy or there were too many big vehicles with bright lights driving around and you couldn't see clearly. And if you'd only follow it if you didn't know you were following it into the work area, then what good, exactly, does the sign do?

My favorite all-time unexplainable sign, by the way, was in front of a house in northeastern Iowa:

Chainsaw on Hand

for all your chainsaw emergencies.