You've probably heard of the phenomenon in which a random stranger pays for the order of the person behind them in line at a coffee shop. According to Starbucks baristas, it happens all the time. The victim of this generous act gets their coffee for free, having their faith in humanity rekindled by a nameless, altruistic coffee shop hero, and the hero gets to feel better than the rest of society for however long the emotional inertia of the deed lasts. It's a win-win... so it seems. I can't help but wonder how exactly this transaction is performed. If you're the hero, are you supposed to guess what the person behind you wants? It would be nearly impossible to guess the price of the order using cash. Do you use a credit card and let that cover whatever the person behind you wants, and if so, how does that work? You have to ask yourself whether you're still a hero if you're the kind of person who uses a credit card ...