Definitions by The clock is ticking

Unus Annus Day 

The one day out of the entire year on november 13 where fellow unus annus fans go out and wear merch and celebrate all the life lessons that Mark and Ethan have taught us.

Bro make sure to wear your merch tomorrow for unus annus day

I wouldn't miss it for the world man

Unus Annus Day by The clock is ticking November 5, 2020