be prepared for a lot of answers--
I have heard two reasonable ideas

In the construction industry, a 9 (cubic) yard truck is the norm for concrete trucks
If you want to buy concrete-- you must by the "whole nine yards" no matter you only need 3 or 4 yards to complete your job.-- Construction companies would roll together 3 or 4 small jobs-- people who wanted several yards, and "sell the whole nine yards" 3 or 4 times--
Since most of these transaction where in cash-- it became a neat way of generating extra cash--

An alternate idea comes from the military-- a machine gun "strip" was nine yards long-- if you fired the whole nine yards-- that was a lot of ammo.

but i am sure others will have ideas-- I am not sure if there really is a definative answer-- but if there is, tsuwm will try to deliver it!


my other obsession