I have been living in the Czech Republic for 5 years now and learning the Czech language ever since — which by the way is considered a language with significant linguistic and cultural differences from English.
Normally, I feel confident in most conversations, though I have experienced some fairly funny situations caused by misunderstandings.
Last year, I went for a cycling trip with my friends. I remember going downhill and there was a curve at the bottom of the hill. I was about to brake, when my wheels slipped and I slid on the sf gravel. My friends rushed to help me. I felt ok, like nothing had happened and then I saw my leg. I had sliced open my calf and was taken to a hospital. I was happy that I could communicate with doctors in Czech since most of the most doctors speak only Czech in Karlovy Vary. Neither English nor Spanish would have helped.
Anyway, the doctor told me that they need to “umrtvit” my leg. I did not know what the word “umrtvit” means, but I knew the word “mrtvý” (Czech for dead). Well, for a whole day and night I kept thinking that part of my leg is dead and that they’d need to reconstruct it.
Luckily, my friends came over in the morning and explained to me, that “umrtvit” means to be put under an anesthesia. I was very much relieved.
By the way, google translate was not very helpful either as my phone battery was “mrtvý” (dead).