A joke I haven't heard before

I will now make today disappear.  The date is 7/30/13.  7 - 3 - 0 - 1 - 3 = 0.  Magic!

Officially, this joke makes sense only in the USA.  Unofficially, Canadians often use mm/dd/yy format for dates, along with dd/mm/yy, which creates a horrible ambiguity.  Come on, folks!  Everyone knows that today is actually 2013 JL 30!