Lots of people don't drink these days. Toasting someone with an empty glass makes no sense. While she had me on the phone, Cater offered some dining etiquette for the drive-through. When you get your food, don't just stay there while you put ketchup on your hamburger. Fix your burger in the parking lot.
Good manners are good manners.
You don't have one set of rules for Cafe Annie and another set for McDonald's. Above all else, don't ever stuff a napkin in your shirt collar under your chin. It doesn't matter that nobody can see you. You should take plenty of napkins. Put one on your lap and one over your tie.