Anyone with a penis entering a ladies room while my daughter is in there(*) won’t have one when they get out.
...and if they go in by mistake, like happens occasionally when in an unfamiliar location, you’re gonna go all psycho on them, too...?
"''scuse me, but you want this door over here."
The difference is then either:
oh, my mistake, thanks. (No prob.) or
but I'm a girl. (You're gonna be.)