In 1965, after being in Italy for only 2 months, I was certain that I was completely fluent in the language.

I was in a train compartment with about 5 other people with a rather cool breeze coming in from an open window. I noticed that a nun sitting near it appeared a bit uncomfortable, but thought I should check with her before taking it upon myself to close it.

When I asked her if she was cold, I unfortunately translated directly from English and got some very strange looks from the other passengers.

The actual meaning of my question was, "Excuse me, Sister, but are you frigid?"