What is meant by the phrase "bought the farm"?

The phrase means that a person died. Although the exact origin of “bought the farm” is not known, one theory suggests that it comes from a 1950s-era Air Force term originally meaning “to crash” or “to be killed in action.” According to this theory, some wartime pilots might express the wish to stop flying when the war was over, return home, buy a farm, and live peaceably ever after. When, tragically, one died as a result of a collision or were shot down, their buddies would shake their heads and mutter, “Well, I guess he bought the farm.” In this case, however, the “farm” was a burial plot.