I know you meant it as a joke, but leaving lights on can at times be more efficient and better for the life of the bulb. Because of the initial charge required to get the bulb lit and the gas within the fixture charged turning a light off and on a number of times requires more energy and diminishes the life of the bulb much faster than if it was just left on. This is particularly applicable to florescent lights due to the increased energy cost of "charging them up (part of why they flicker when you first turn them on).