This kind of happened to me when I visited New York like 20 years ago. I ordered an ice coffee, and the lady asked me "what size?" I looked at her confused for like 30 seconds until I finally figured out that she didn't want me to explain what ice is... I still feel stupid thinking about it.
Heh, reminds me of an old joke. A woman gets off a plane with this tall African man with wild hair, tribal dress, the works. Her mother is waiting with a shocked look on her face, and when finally they meet the mother says, 'You fool, I told you to marry a RICH doctor!'