Your mom tells you to go to the market and sell your only cow. As you walk along, you encounter a man who wants to trade you a handful of beans for the cow. "No way," you say. The stranger tells you these are magic beans. You hand over the cow, get the beans, and end up running from a giant in a magic sky castle. As you flee, you think, "How did that guy get me to trade a perfectly good cow for those beans?"
There's a science to persuasion, and if you know how it works, you'll know how to avoid falling for a deal that's too good to be true.