Offer them both keys. This works particularly well if the bathroom keys have the bathroom they go to attached (like the little skirted figure or the little unskirted figure).
Alternatively you might just have to assign gender to people which is uncomfortable.
Boo gendered bathrooms, yay for a GREAT answer.
Put them in a little basket! They do this at a Starbucks I’ve been to. Just hold out the basket. It’s less awkward than...
I work at a pool where the only entrances are though the mens or womens changing rooms. I constantly have to direct...