The Ides of March

The admonition to beware of the "ides," or 15th day of March, appeared in William Shakespeare's play Julius Caesar. According to the Old Farmer's Almanac:

"The Ides of March has long been considered an ill-fated day. The ides were the 15th days of some months in the ancient Roman calendar. The word ides derives from a Latin word meaning 'to divide.' The ides were originally meant to mark the full Moon, but because calendar months and lunar months were of different lengths, they quickly got out of step. In fact, the ancient Romans considered the ides of any month unfavorable, as well as the calends (first of the month) and the nones (ninth day before the ides). The concept of unlucky days survived Julius Caesar (who was assassinated on March 15, 44 BC -- talk about bad luck) and calendar reforms."

Mine's been pretty good... so far.