When they inform you that the shake machine is broken, have a backup plan. So be prepared. Get a Coke instead. Don't sit there wondering whether you'd rather a Dr. Pepper. Have your money ready.
Food costs money.
After you place your order and pull up to the window, the nice person will ask you for some money. This shouldn't come as a shock. Get your food, drive away. After you pull up to the final window and receive your food, just leave. If you find it necessary to check your order, fine.