What is the greatest Halloween prank in history? I have always considered it to be the Mercury Radio Theater on the Air’s Broadcast of War of the Worlds. Its audience thought the show interrupted for an emergency broadcast was real. How could they then know Grovers Mills, New Jersey and Martian landings were completely fiction? Panic followed. In 1939 the perpetrators’ mischief night broke no laws so they were not held responsible for their trick or treat.
The FCC put new laws on the books to avoid similar situations–the reason for the warning words that often appear on radio and TV.