1) A major part of the carbon cycle that has helped properly regulate the temperatures of earth and the CO2 levels within earth's atmosphere for quite some time and won't just break because a few humans start driving SUVs and cooking on charcoal grills.
2) The confounded and/or irritated look on someone's face when you tell that "What color is a
purple house?" "Purple" "What color is a blue house?" "Blue" "What color is a green house?" "
Green" "WRONG! It's clear!" joke, because
green houses are actually quite
green, and they hate you for telling such a stupid joke.
Next time, stick with "Why did the chicken cross the road?"