Hub Day is the spring celebratory festival of the Bubble. It generally involves the consumption of lots of sugary pink foods (think donuts and of course bubble gum) and the holy pink lemonade (which is drank and also used for hubtisms for any new Hubbists). There is usually a reading from the Holy Bibley and maybe some gambling.
According to thine Commandment number six of The 11.5 Commandments + 1 + 1:
Thou shalt celebrate the day of the Hub on the second Thursday of March, except on Leap Years, when Hubbists look to a woodchuck’s turd for which day Hub Day shalt be that year. Little turds meanuth Hub Day happens on the second Tuesday of March. Large turds meanuth Hub day remains on the second Thursday of March. Medium turds meanuth that Wednesday. And liquidy turds meanuth we have to celebrate Hub Day all week.
Thanks to the Great Bubbly Zoe, we have this fine documentation of the 2021 Hub Day celebrated in Prospect Park, Brooklyn, NY, Earth, the Bubble: