If something from the government crashes on to a farm - like a military plane, the government 'buy the farm'. as in the land that it destroyed. The pilot is dead because of the impact...
--James Bradley, in Flags of our Fathers
Bob: "Pretty good. You know that farm he was going to buy? The big one in Kansas with all those cows and shit, you know? Yeah, well he bought it."
Billy: "No way, you mean he bought the farm?"
Bob: "Yeah isn't that the bomb diggity?"
Billy: "You're sick, man. That's really fucking sad."
"bought the farm"
Crewman: "Guess ya bought the farm ehh?"