This is an awesome phrase, but explaining it to M was an exercise in futility.

But then she brought up おっちょこちょい and it sounds pretty appropriate. Or am I misinterpreting?

Ah, I guess there is some overlap. But AFAIK occhokochoi refers to general airheadedness, rather than the specific behind-related thoughtlessness.

Got any ideas for a good way to translate "They don't know they're born"?

(No, it's definitely NOT complimentary!)

None of my sources have anything. I'm gonna have to throw that one to the gallery.

I'd like something in 知らず. Is there a good old-fashioned word for "birth"?

Somehow 誕生知らず doesn't quite do it for me.

Hmm...the gallery is silent....