As a Canadian teenager, I worked at Tim Horton’s. This is a chain of fast-food restaurants that serves mainly coffee and snacks. Many of our customers are gruff, grumpy, caffeine-addicted men. I was the typical, perky, cheerful teenaged girl cashier. I loved that job, because I was REALLY good at it; efficient and fast.

Mr. Grumpy comes in one day and interrupts my friendly greeting with an abrupt, “Two medium, one black, one with milk.” I pour his coffees, lid them, and promptly place them on the counter. I did this quickly, deliberately omitting the step of using a white pencil to mark the lids, which we normally do to indicate which was which.

He looked at his cups, then looked at me like I was an idiot, and sarcastically asked, “How am I supposed to know which is which?”

With an almost imperceptible jerk of my wrists, I moved the cups enough that a tiny drop appeared on the lid of each cup through the vent hole. One drop was definitely black, the other clearly contained milk.

“Would you like me to write it down for you, sir?” I asked, smiling politely.

“Nope, that’ll be fine, thanks.” He paid me the 2.20 and left. Still gruff, but I think I detected a tiny flicker of amusement in his eyes.