I once had an idea for an erratically-scheduled holiday called "arbitrary apocalypse day". The day after each AAD if the world hasn't ended, you'd roll a D-10

I once had an idea for an erratically-scheduled holiday called "arbitrary apocalypse day". The day after each AAD if the world hasn't ended, you'd roll a D-10 3 times to get a number of days between 0 and 999, and that's the new predicted apocalypse date. You'd select a cause at random (i.e. nanobots, aliens, meteor, supervolcano, nuclear war, pandemic, etc...) and tell everyone that doom is nigh. In the end, I didn't promote it heavily and forgot to celebrate on the appointed day (or choose the next date). Maybe I should start it back up again.