Besides the holidays which math people already celebrate (like Pi Day), we started our own: Math Storytelling Day. It’s roughly around the time of the year when the Natural Math project started in 1996, and a couple of people also have birthdays on that day. It’s kinda neat that by now it comes up in web searches. I sometimes run design-a-holiday activities with groups: either we design it together, or each person designs a Day for themselves. “On your Day, we celebrate by…” MLK Day is an inspiring model of a community Day.