I ran across this
while searching for interesting maps. It is angmessen for this thrad, but is about a joke being used as a weapon, not a joke itself. The joke itself is withheld for safety reasons. I found it hilarious.
Originally Posted by Alternative History WLD
During World War 2, Ernest Scribbler heads a secret department at Bletchley Park. He is discovered at his desk, quite dead, with a single note written in front of him in German. This death is naturally suspicious, and he is immediately suspected of being a spy. The note is read by translators at the facility, fluent in German just like scribbler, who immediately begin laughing uncontrollably. Hearing or reading this Joke results in the deaths of almost a tenth of native German speakers, half that number if they are fluent in German as a second language, and half that again of those who have some level of conversational German. Even those with barely functional German, or those who speak it and survives are incapacitated once they get it, sometimes for hours or days, in fits of laughter. Once the Joke has been heard, the survivors are constantly sensitive to it. Anything that reminds them of it, even the sound of laughter, reduces them to hysterics once again. It is estimated to be around 60,000 times funnier than the greatest pre-war joke.