Otherwise know as "Die Like a Pirate Day"

http://dayoftheninja.com/index2.html

As last year (and every year from now on), December 5th is the Day of the Ninja. Plague your co-workers with ninja-ness and wear a ninja mask to work! Got the day off? Run wild in the streets, or dress like a ninja at the mall! Just show the world that YOU ARE NINJA!

Now, get out there and do us proud...!