Sign at the bagel shop a week ago:
If you don't know our pronouns, please use 'they'.
Bagel shop cashier today, as I put in my order after my agender partner's:
Are you eating with her? I'll put you on the same ticket.
Bagel shop server today, arriving with bagels:
Here you go, guys.
The sign is gone now; it didn't last long. I'm not saying it's wrong, but if you are going to take a firm stance you should probably not half-ass it yourself.