How you pay for the next person sh*t... if you dont know what they order?
It's a drive-thru.... The orders are in a queue so when you get up to pay for yours and they cash you out the next order/total comes up, this is when you can say " hey how much is the next person's order?" And pay...
(Source: I managed a KFC part time for 10 years as a 2nd job when my kids were young)