To be frugal with trivial matters and reckless with more significant ones. The phrase describes the incongruity of turning off water at the spigot but leaving the bung, or stopper, off the reservoir. A: "Dad never lets us turn the heat up in the winter because it's too expensive, yet he ignores any problem around the house until it becomes a major repair." B: "I know, he always spares at the spigot and spills at the bung." I know you like to spare at the spigot and spill at the bung, but you would save so much money in the long run if you got a new car, instead of repairing all these nagging issues.