The two-day celebration from June 30th to July 1st for Discordian Popes to symbolically excommunicate each other, then to de-excommunicate each other.
1st Pope: Hey buddy, I'm fnord to excommunicate you!
2nd Pope: I'm fnord to de-excommunicate myself, then I excommunicate you!
3rd Pope: Happy June 31st For Popes! Fnord!