I remember my mother always using the phrase "Once in a blue moon." Well, today is that day. Tonight is the second full moon of the month which is known as a blue moon. I can attest to the fact that full moons do make people act strange. Work a 3rd shift during a full moon at my restaurant after the bars close and you'll see a big difference in my customers. I hope for the sanity of my staff they're not twice as bad tonight.
More info on blue moons here