Many many years ago I walked into a French bakery that had just opened up and was getting lots of good press. I was just out of college so money was a little tight so I scanned the menu board and the cheapest thing was a baguette. When it was my turn to order I asked for one "bag you et". The lady gave me a snotty look, pronounced it correctly with a questioning inflection. I sheepishly said yes.

I was in a similar situation last weekend. We were in a bakery and their challah rolls looked really good. I ordered one but didn't know how to pronounce it. I opted to pronounce the "ch" like "chalk". I just looked it up and I was wrong. The two acceptable pronunciations are either "hall uh" or "call uh". At least I didn't get a snotty look this time.