Better yet, I Can Has Cheezburger has a whole gallery of these things. Besides this one, the potassium joke is one of my favorites.
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.