We commonly use the expression “the whole nine yards” to mean absolutely everything. The origin of this expression stems from the military. As Alan Axelrod writes,
The length of a complete standard .50-mm machine gun ammo belt: twenty-seven feet.
To feed the gunner the entire belt was to give him (or the enemy target) “the whole nine yards”; hence the popular expression for giving, getting, or doing absolutely everything.
from – Alan Axelrod, Whiskey Tango Foxtrot: the Real Language of the Modern American Military. New York: Skyhorse Publishing, 2013, p. 205.