"Whoever wants to go to China must cross seven seas"
C-Day is short for "Candy Day" which usually means when deployment for an operation commences. It is called "Candy Day" because before deployment candy is usually passed out to G.I.s from charitable organizations. [http://en.wikipedia.org/wiki/Military_designation_of_days_and_hours]
Michael Aschauer, http://m.ash.to, 2008