...except after "C"

1. The military theory:
   It has been purported that either the RAF Spitfire's machine gun bullet belts or the B-52 Bomber's bomb racks were 27 feet long, and thus that emptying them would result in giving the enemy "the whole nine yards". Unfortunately, there are two dings in the armor of this particular theory. The first is that the phrase did not appear in print until 20 years after World War II, making it unlikely to have a military origin. The second is that no evidence exists that would suggest a standard length of these or any other military apparatus to be 27 feet.
2. The garment theory:
   Various versions of this theory suggest that a standard amount of fabric to make a men's suit or a bridal gown is 27 feet. However, a typical tailored three-piece suit for an average-sized man takes no more than 5 to 7 yards of cloth, and even Princess Di's ridiculously long train was 2 feet shy of the 9-yard mark. The one factor in favor of this theory is that it could relate it to the phrase "dressed to the nines". For another (albeit ribald) take on this theory, check out Angus and the Kilt.
3. The burial theory:
   Another assertion is that burial shrouds are traditionally made from 9 yards of cloth or that 9 cubic yards of dirt is removed to open a grave. The latter seems plausible, since that would yield a burial plot that is 6' X 6' X 6'9".
4. The prison theory:
   Still others have argued that the distance between the cell block and the outer wall of a prison is 27 feet, or that the height of the prison wall is 27 feet, and thus in order to escape, one would have gone "the whole nine yards".
5. The torture theory:
   A less popular theory alleges that a medieval practice of disemboweling a person one foot at a time would result in the ultimate punishment being inflicted at 27 feet (the length of the human small intestine) Related to this are stories of making victims walk 9 paces over burning coals and the official length of rope in a hangman's noose at 27 feet (although it is spelled out in Delaware's manual for execution by hanging as 30 feet).
6. The football theory:
   Some might advance an alternate theory about the phrase being laced with sarcasm in relation to a football play that came up a yard short (ten being the number of yards needed for a first down). However, no one is ever able to actually point to a game in which a player was said to have gone "the whole nine yards".
7. The ship's masts theory:
   Others contend that nine yards is not a measurement of length, but rather the number of horizontal poles that hold up the sails on a square-rigged sailing ship. A captain who had sent up all the sails for maximum velocity would thus be said to be giving it "the whole nine yards." However, nine was not the typical number of "yards", and "whole" is an odd choice of words vs. "all".
8. The truckload theory:
   Nine cubic yards is said to be the full capacity of (a) a West Virginia ore wagon, (b) a New England coal truck, (c) a standard garbage truck, and/or (d) a ready-mix concrete truck. From the August 1964 issue of Ready Mixed Concrete Magazine:
   

   "The trend toward larger truck mixer units is probably one of the strongest and most persistent trends in the industry. Whereas, just a few years ago, the 4 1/2 cubic yard mixer was definitely the standard of the industry, the average nationwide mixer size by 1962 had increased to 6.24 cubic yards, with still no end in sight to the demand for increased payload."
   

   Modern trucks range from 6 to 10 cubic yards in capacity, with the average around 9. Given that the first printed occurrence of "the whole nine yards" appeared just a few years later (1967, The Doom Pussy, by Elaine Shepard) it is entirely possible that this phrase indeed arose from the construction industry.

We may never know what was originally meant by "the whole nine yards," but at least we can be reasonably certain that the average modern cement mixer has the capacity to fill a standard grave with concrete. I'm not sure why it's helpful to know this.