The Whole Nine Yards

[haukehaien]

The machine-gun belt explanation simply doesn't work. (All of these things have been pointed out before, but people keep ignoring them)

1) MG belts are measured in rounds. Not feet, not yards, not metres, not Babylonian cubits nor any other unit of length. If a unit besides rounds were to be used, it would most likely be weight, that being the thing that would concern a pilot or trooper.
2) If the phrase did come from WWII MG terminology, why doesn't it show up until the 1960s? We've got lots and lots of writing from that war, plenty of accounts by people who lived and fought through it... and nobody uses the phrase until the mid 60s.

My suspicion is that it is going to be extremely difficult to track down. If Cecil Adams, Evan Morris, and Melanie and Mike of Take Our Word For It (www.takeourword.com) can't come up with an answer, then the answer is very obscure indeed. What this means for us is this: any answer we have, which does not come with an appropriate citation and time period, is almost certainly wrong. Of the explanations posted, the dirty joke seems the most likely. It has the right time period, it's not related to anything in real life (which would explain why nobody's been able to point at something and say, "See! ______s have always been nine yards long!")

The world may never know.