Here's a word that popped up out of nowhere. What the hell is a "Carbon Footprint"?!?

Carbon Footprint: It is an imaginary phenomenon that is obbiously invisible, akin to perhaps an imaginary friend. It is the amount of carbon that people emit and what they imagine themselves to be staining the Earth with. In order to erase their carbon footprints, some bright fellows have invented another imaginary phenomenon known as the Carbon Credit.