Editor's note: Before you read the posting below, check this page on 'The origin of the whole nine yards'.
In Reply to: The whole nine yards... posted by Alison Causton on October 22, 2002
I heard that it refers to the length of a machine gun belt being about 27 feet
If you used all the bullets on the belt in fighting off the enemy you gave him the Whole Nine Yards.
But your mother might be right too.