Customer: Everyday you charge me money for a cup of coffee. It will be wonderful if you serve me coffee free of charge today.

Waiter: Sir, everyday you drink coffee from a filled cup. It will be wonderful if you drink it from an empty cup today.

顾客：你每天都收我咖啡的钱，要是今天不收就太好了。

服务员：先生，你每天都从盛满咖啡的杯子里喝咖啡，要是今天从空杯子里喝就好了。