#4: Open the Door First
Some warnings exist because someone, somewhere, did exactly the thing you’re not supposed to. This sign politely reminds shoppers to open the door before entering, as though there’s been a steady stream of people trying to walk straight through the glass. It’s obvious advice — and that’s the joke.

Placed at a pharmacy entrance, it doubles as a safety measure and a bit of unintentional comedy. Maybe the doors are so clean they’re invisible, or maybe people are just in too much of a rush. Either way, it’s a hilarious precaution against forehead smudges.
