I had a craving for french fries one day, so I pulled up to the drive-thru of McDonald's.
* Me: "I'd like a large french fries please."
* Clerk: "Would you like fries with that?"
I got sort of confused at this one and told him no. He told me to pull ahead, so I did, and then he asked me why I was sitting there.
* Clerk: "I thought you didn't want fries."
* Me: "No, I ordered a large french fries."
* Clerk: "Ok. Do you want fries with that?"
Since saying no the last time had gotten me nothing, I figured I'd better say yes this time.
He gave me two large fries.
Things People Said in Restaurants has a large and entertaining collection of anecdotes like this one, as well as ambiguously worded menus and signs that don’t quite make sense. Link -via Cynical-C
Best example of staff not knowing what they were talking about (not restaurant related, unfortunately) was the guy who told me to download my modem drivers off the internet.