‘Once in a blue moon’ to describe the rare occurrence of an event or appearance of a person. The ‘Blue Moon’ refers to a fact when we have 13 full moon in a year in place of 12. When the blue moon appears, we have two full moons in a month.
This year it’s July 31st, which is a Friday and also coincides with Clam Fest.
I predict crazy behavior, possible arrests and street flooding.