The other day I went to sell some books at The Strand bookstore. They have a separate desk in the back for selling books. I brought in a bag and two clerks started sorting through them.

Then another guy lined up behind me. One of the clerks said to him, “You here to sell books?” He said, “Yes.” The clerk responded, “Wait in the line outside.” The guy went outside.

Thirty seconds later he was back. The clerk repeated, “Wait in the line outside.” The guy said meekly, “There is no line outside.”

The clerk sighed, looked at the other clerk, and sarcastically said, “There is no line outside.” The other clerk said gruffly, “If you can’t figure out the line, then you can’t sell books here.” The potential seller walked back outside meekly.

A minute later, a girl walked up with books. “Wait in the line outside,” said the clerk again. She walked outside. A few moments later, she was back. “What are you doing?” She said, “Selling books.” He said, “The line is outside.” She walked outside again. The clerks laughed. “Let’s see if the Mensa society out there can figure out how the line works!” And they laughed some more. As if both these customers were complete morons.

Lucky for me, I had arrived moments before these other two. Because I sure had no idea there was a place outside to wait in line. Or that “there’s a line outside” actually means “form a line outside.”

I think a lot of people who work in customer service make a similar mistake in laughing at customers or making fun of them behind their backs (PEBKAC comes to mind).

It can be a dangerous trap. Sure, any one customer might be stupid. But if multiple customers are repeatedly making the same mistake, maybe it’s not a mistake on their part. Maybe it’s a mistake on your part. If no one can figure out where to wait in line, maybe that’s a sign that you’re not doing a good enough job explaining it.