So what question has surprised you the most over the years? Anything pop to mind? " 'Why does Japanese have virtually no swear words, while Korean is chockablock with swear words?' The answer was that the samurai culture of Japan made it dangerous to run the risk of insulting someone, so people were cautious about how they spoke in Japan," says Frank. "There was never a similar tradition in Korea."

How is that a question of economics? "It's the cost-benefit principle. I'd like to insult this guy, and in Korea, I can, but in Japan, it might be really costly if I do," he says.

One thing that seems, well, crazy, is when hotels charge different rates for the same kind of room. Aren't they in danger of annoying their customers? "If you can figure out ways to charge people different prices, that enables you to offer a better deal for everyone. There's the example in the book of Apple laptop computers on sale for different prices in black and white. You might get offended if you bought the black one and realized it was the same as the white one and that you paid a premium for it. But if you reflect on the fact that the company is able to expand its market, the cost of producing extra machines is very small. So the fact that they're able to expand the market means they can set a lower price for both machines. If they do it with what I'm calling the hurdle method, they put a hurdle in your path and tell you that if you want the cheaper price, all you have to do is jump over a hurdle - like buy the color you don't like, wait a year and buy the paperback, or ask about the special price [when you make a hotel reservation]. As long as [those choices are] available to people, you can't really complain that they charged you a higher price," says Frank. "[You] could have gotten the lower price; [you] chose not to."