To be even remotely consistent with the confusion inherent in the TG crowd the “flag” should actually be something other than a flag. Maybe a carved wood sign?
And it should be badly secured so that it threatens to fall on passers by without warning.
And “flown” over the door of a women’s restroom.
Or maybe they could make a flag that changes color like the old “mood rings?” This way the trannie could just go to the restroom that fits their mood.