Sorry to start ANOTHER tipping thread, but I don't know what the etiquette is when you order for delivery and find that the restaurant screwed up on the order. I don't order out for delivery very often but did it for lunch today. They messed up my order but I just kept it as the error was small. But if it had been a large error or they completely left something out I would have had to call up the restaurant to amend it. Do you tip the delivery guy again when he comes back with the amended order? It's not his fault that the order was screwed up, yet he has to make two trips. And if you do tip, how much?