Is it Actually Harmful to Perpetuate the Idea Girls Don’t Poop?

Regarding a post I made yesterday and comments therein, it got me thinking on something:

Is it really a harmful idea to boys and girls alike to "teach" boys that girls don't poop?

As in, telling boys that girls don't do this thing, but girls do it, thus setting boys up to be otherwise disgusted or such, and setting girls up to potentially feel gross, undervalued, and/or selfconsious because of how boys react to learning girls poop too.

Or is this overthinking a simple running gag between the sexes, and it's a harmless joke?