Energy Saving

I’ve just returned from calling on a friend down the road who has a teenage daughter. She came downstairs to join us, and her father remarked “I trust that you’ve turned all those lights off upstairs”
“But Dad, they’re all energy saving lamps, so the more we use the more energy we save”
Harassed father’s comment was to the effect that she sounded just like her mother who any time now would be coming in and explaining how much money that she’d saved in buying all these clothes in the sales.