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!