I had a friend in high school who spent part of her summer working at McDonald’s. And one of the reasons McDonald’s makes so much money is that they’ve mastered the art of up-selling.

If you’ve seen the documentary film Super Size Me, you know what I’m talking about. You order a hamburger and fries, and they try to sell you a bigger hamburger, a bigger envelope of fries, and a much larger drink to suck out of a cup that you will discover is too huge to fit into an armrest cupholder.