Aha Radio Station

This might be the only planetary-scale case of collective suicide in cosmic history. Jim Jones Star was a planet as ordinary as they come: average climate, average resources, average civilization. That is until the "Aha Radio Station" opened up on a neighboring planet.
Aha Radio Station was founded by a group of (self-proclaimed) Aha believers, aiming to spread the spirit of Elation. Their method was to use high-power radio telescopes to broadcast jokes they'd written themselves to the entire cosmos.
After over a century of enduring unfunny jokes, the poor inhabitants of Jim Jones Star finally suffered a mental breakdown and brought their own civilization to an end. It is said that the final straw was the line: "Humans are born from humans, but imagenae are simply created from imagenae-tion."