What does NAVY stand for?

I heard this back in 91 when I was going through boot camp, Never Again Volunteer Yourself, well yesterday, I lifted my right hand and said these wordsI, Sean Dustman, do solemnly swear that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; and that I will obey the orders of the