It is so low-tech that Gen Z’ers and other digital natives may faint (or perhaps the avatar in a VR game that they are playing may faint) to learn that one of the greatest inventions in the history of our species is the humble do-not-disturb sign. Indeed, this magical placard is like having a very own private Gandalf shouting: YOU SHALL NOT PASS! However, the glory of do-not-disturb is not limited to hotels, motels, and teenagers’ bedrooms.