Precursors
A story that ran for several weeks in the Sunday comics of Li'l Abner during 1967 concerned the creation of a joke, never actually revealed, that was so funny that anyone who heard it immediately died laughing. For safety reasons, government agents somehow decided to keep the joke hidden in the protective custody of Abner Yokum. Meanwhile, comedian Bob Hope learns of the existence of this "Funniest Joke in the World", but not about its deadly effects, and decides that he wants to recite it on his next television show. He procures the joke from Abner, and the government agents learn of this development too late to prevent him from reading it on national television. It turns out, however, that before Bob Hope obtained the joke from him, Abner had read the joke, not understood it, and substituted his own favourite joke. It is this joke that Bob Hope reads on the air, to no harmful effect whatsoever.
The 1943 war-time story "Nothing But Gingerbread Left", written decades before by science fiction writer Henry Kuttner, has a very close premise. Rather than a joke, a marching song (in German) is used as a weapon against the German soldiers. Engineered by American linguists, it is by design such a catchy song that the soldiers cannot stop singing it, and eventually they can think of nothing else. At the climax, Adolf Hitler is ready to deliver a critically important speech, but begins chanting the marching song.
Read more about this topic: The Funniest Joke In The World