Revenge of the Sixth

Etymology
. From the name of the Star Wars movie , and a day of the month of similar sound to "Sith".

Proper noun

 * 1)  The Sixth of May (May 6). The third Star Wars Day, the second day after Revenge of the Fifth (May 5). Sometimes used to celebrate the Dark Side, when May 4 is used to celebrate the Jedi.

Usage notes
May 6th is celebrated when May 5th is not celebrated.