When customers in a cafe/restaurant/whatever order a list of ten items at once, only to be told that they need to repeat them one at a time so they can be put into the POS system correctly. I'm good, but not that good. I can probably remember three or four things, but not ten. Oh, and this especially applies to those who want extra this or no this as that also takes more time to add to the order. I can only click one button or write one word at a time. By the time I've located the next few items on an incredibly complex system, chances are, I've forgotten the ninth or tenth item. Don't just walk off and expect me to put these invisible items on your tab!
/rant over.