The word "Cf" (pronounced "seff") is an abbreviation of the word "Seff", which is an abbreviation of "selvfølgelig", which means of course. Cf is a very cool word used only on chatrooms and facebook, never when you talk (when you talk, "seff" is used instead, although these two words are pronounced the same way), and only by the wickedest of the wicked.
Short for Canadian Forces, the overall designation of Canada's Army, Navy and Air Force. Rather than three seperate branches, the CF is under one unified command, and members of all three brances must undergo the same basic training.
Therefore, if a CF member wishes to change branches, they don't have to go through "boot camp" a second time.