My aviation-obsessed son David and his younger siblings recently went on a paper-airplane-making binge. So now there are approximately 67 paper airplanes in my living room. This afternoon I caught Brian about to filch some of my printer paper in order to make yet more flying machines, and I snapped, "Stop it! This paper doesn't grow on trees, you know!"
Yet another time when you've got to wonder why I'm allowed to homeschool my children...