If you order non-fat drink, the lady may start ...
If you order non-fat drink, the lady may start using 2% & if you catch that & ask "is that non-fat?" she will acknowledge it isn't & ask if 2% is ok?
If you order non-fat drink, the lady may start using 2% & if you catch that & ask "is that non-fat?" she will acknowledge it isn't & ask if 2% is ok?