I normally don't mind, because fast food places are usually all rush rush, and if you explain the problem they fix it immediately.
However this one time, my friends and I (5 of us total) did a midnight run through a McDonalds drive through. We needed to split the order, because we were all paying by debit. We asked if this was fine, and they had no problem with it.
So we all make our orders, get cited a price, and drive up to the next window. We all proceed to pay, and the guy working there hands us two bags. While we're waiting, we check those two bags, and find that both orders are wrong. One guy was missing his drink and fries, while the other guy had been given two of the wrong burgers.
No big deal we think, we'll just get them to fix it when they bring the next batch.
Five minutes pass, so we knock on the window. The guy working there pops it open and asks us what we're still doing there.
Hello? Where's the rest of our food? We all payed for our food seperately, how did you miss three orders?
We explain the problem (our missing orders and the incorrect ones) and he huffs off to make more food. He passes us three more bags, only one of which is correct, and still fails to correct the original mistakes.
We complain again, he brings us more food, but still fails to fix everything. In the end, he practically threw food in our window and told us to get lost.
I wouldn't have had such a problem with it if he hadn't been generally rude, acting like us being their was such an inconvienience the whole time.