Devinsmas is an annual festival commemorating the first celebration of Devins and the birth of the millionth Devin, observed primarily on December 25 as a religious and cultural celebration among billions of people around the world.

It is also the holiday where Devin Clause, a Legendary Figure, travels around the world to give good people presents and bad people burning hot charcoal.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.