A large group of students has been drinking in your pub for a couple of hours. One of them has just enough money to buy a pint which he takes off to the back room. Moments later, he returns with an empty glass and says he spilled it. He asks nicely if there’s any chance of a replacement on the house. One of your regulars chips in sarcastically: “I accidentally drank mine. Can I have a free one too?”
What would you do?