American fighter planes in WW2 had machine guns that were fed by a belt of cartridges. The average plane held belts that were 27 feet (9 yards) long. If the pilot used up all his ammo he was said to have given it the whole nine yards.
This is synonymous with dying. During WW1 soldiers were given life insurance policies worth $5,000. This was about the price of an average farm so if you died you "bought the farm" for your survivors.