If your idea of delicious (and convenient) dining is eating a pizza while watching the big game, you're not alone. Pizza is a $30 billion industry in the United States, and the average American eats around 26 pounds of pizza per year. That's a lot of pie, and chances are, at some time or another, and probably more often than not, you've opted for pizza delivered to your door. It's usually pretty fast, and you can't beat the convenience. The clean-up can be a breeze, too. Eat it straight out of the box with some napkins, and you won't spend the rest of your night at the kitchen sink. The world of pizzeria pizza isn't all pepperoni and piquant sauce, though. The pizza guy who delivers your pie may look fresh-faced and friendly, but he could be harboring a few secrets you should know about before you spring for that hefty -- or embarrassingly stingy -- tip.