A Monty Python sketch where Ernest Scribbler creates the funniest joke in the world, and dies laughing. Numerous people attempting to investigate also died laughing upon reading the joke. It was finally retrieved by the British Army, and after careful testing, the joke was translated into German for use on the battlefield. Because the joke was so lethal, translators were only allowed to work on one word; a translator who unfortunately saw two words had to be hospitalised. This sketch is available on the CD-Rom Game of Monty Python and the Meaning of Life.
The concept of fatal hilarity is not an uncommon one. David Foster Wallace's novel Infinite Jest deals with a videotape containing a movie so entertaining that anyone watching it loses all desire to do anything else, eventually becoming comatose and dying. A Star Trek episode also dealt with the nature of addictive video games which were so fun that the users lost their free will. Red Dwarf describes similar video games in Better Than Life, which is both a book and an episode of the television show.
In addition, much of comedy slang deals with the concept of death, e.g. "I killed them out there".