My wallet was stolen in a cafe in Jerusalem when I was a rab student; I panicked & (w/my then-bad Hebrew) could only think of a phrase from Talmud study (so: Aramaic) to tell the waiter what had happened so I ran up to him and said, in what turned out to be in modern Hebrew: “I lack pockets!!”
There's an Apocryphal academia story my dad used tell, about a professor who got lost in Rome. He didn't speak Italian so he went up to a cop and asked for directions in Latin.
The cop replied back in Latin "Sir, it seems you haven't been here in a very long time".
Since the Catholic Church still publishes all it's important stuff in Latin the curia are all supposed to study it. For decades (I think he's dead now) the Latin master (who was from Chicago) complained the Italians all cheated; by just tacking latin endings onto Italian.
I'm sure it grated, because one of the big differences (for those who don't know) is how word order shades meaning.
E.g. in Russian (another declined language). The same three words can be "I don't know" and "It is unknown to me".
An ancient Greek professor of mine once said he was confident of reading the Greek road signs until he discovered that reading ALL CAPS Greek at 100 kph is a whole other beast entirely.
When I was in China I was forever confusing the words for 'cheap' and 'pretty' (they're not actually all that similar but they do both start with a 'p' sound), and it turns out there's really no situation where you can confuse those two and come out okay.
I was having lunch in Nice and tried to use some of my -40 words of French to tell the waiter I was done. Turns out “Je suis finis” means “I am dead”, which I figured out after his offended reaction and the nice lady next to me, both of when were telling me in French (“mort”) what I said.
My father did some research in E. Germany in the 1980s (i.e., before widespread English bilingualism), and evidently ran into some confusion at a market when attempting to buy six (sechs) units of cheese (Käse) with his pronunciation of "sechs" vs. "sex" and "Käse" vs. "Kasse" (cash register).
