Happy Beyoncé Day! Source: Michael Buckner / Getty Any self-respecting member of the Bey Hive already knows that September 4 is Beyoncé's birthday. The number four holds significant meaning for Bey-her husband Jay-Z's birthday is December 4, their wedding anniversary is April 4, and Blue Ivy's middle name, Ivy, is a nod to the Roman numeral for four (IV)-making her milestone 44th birthday all the more special! Fresh off of her record-breaking Cowboy Carter Tour, our generation's greatest performer is probably off on vacation, enjoying some much-needed rest with her family-just like she was o...