It means, "don't call me, I'll call you."

Did you know …

That “quantum” is just a made up word? It’s true!

But wait, you might be saying, aren’t all words made up? Except for the words naturally produced by babies and animals (e.g., “bark,” “burp,” “raaa,” “huuurk,” etc.), don’t words exist pretty much because we decided they should? Well, yes, that’s true, but “quantum” is particularly made up.

The Swiss physicist Leonard Euler was the first person to use the word, and he only ever said it because he couldn’t think of a single real word when one of his mistresses asked him why he needed to leave so early in the morning. As I understand it, she had simply inquired where he was going, baby, and wouldn’t he rather stick around and get breakfast with her later? With literally no excuses at hand, Leonard uttered a random syllable, and then one more, and then ran off her balcony.

Apparently the new “word” was still in his head when he sat down to do some “chill-out math” half an hour later, and it stuck around through his ensuing publications.