If she was honest or had any brains the first thing she should have asked a small business was can you change a hundred.
I wouldn’t hold my breath waiting for the check, you’ve been had.
Of course you may be lucky, she may have just been stupid, there are a fare share of those people out there.
At my store you pay first, then you get your food.
This serves two purposes, the first one is what I tell the odd customer when they ask why they have to pay before I serve them. It is, you don’t want to be fishing around in your pockets or purse for money with a hand full of food do you. They smile and say that makes sense.
The second reason is, to many people come to the window and order what they want, then realise the don’t have enough cash to pay for it, so they down size their order. Doesn’t do me much good if I’ve already made it.