It was my first day in class in an American high school, and I didn't speak the English language. Although, I knew the very basic words.
Where I came from, we had to get teacher's permission in order to leave the class. I thought that rule applied in every class room. I turned around and asked the fat kid behind me "What teacher's name?". The kid told me her name is "Miss Biatch", I wrote it down to practice to pronounce it right.
So I raised my hand and got up and said "Miss Biatch, may I go toilet?".... This is when the whole class started laughing. I knew something wasn't right. She was shocked, so she took me outside the class, because she knew someone taught me the word. I pointed at the fat kid, and he was suspended for three days. :)