Bad English Lesson

I’ve been teaching English to a couple of my friends here, and the other day I tossed in a phrase they’d never heard before:

After I said it, I realized I’d made a rather important error, so I corrected myself:

I also accompanied it with a raised index finger moving side-to-side with my head moving from side-to-side at the same time, but in the opposite direction of my finger.

My friend Florence looked at me with great interest, and asked, “And when would you use this expression?”

I wasn’t quite sure what to tell her.

(After I said it, I realized that I probably shouldn’t have since if the phrase catches on, someday in the future you might go to a café or restaurant in Paris and the waitress will tell you to do just that…and you’ll know who to blame.)