I made a huge mistake in class with my 10th grade students this afternoon. Chinese is a tonal language. This means that a sound can be pronounced four different ways - high, falling, falling/rising, and rising. Each one of these has a completely different meaning, so it's extremely important to get it exactly right.
I was explaining what a Russian czar (or tsar) was and I was trying to get them to pronounce the word correctly. I told the students that we don't have a good representation for the sound in English, so we use the weird combination of "zc" or "ts," but it's exactly the same pronunciation as a word beginning with "c" in Chinese. I used the very common family name "cao" as an example. I didn't actually say the word, I just wrote it on the board without the specific tone.
What I failed to remember was 1) the fact that high school students will twist anything and everything to make it off-color is a global phenomenon, and 2) "cao," said the right way, is one of the dirtiest words in the Chinese language. When the entire class erupted in tittering and laughter hidden behind their hands, I figured that I had done something really bad and ignored it... but I didn't realize just how bad until after class when I got out my dictionary!
Having never said anything really stupid in Spanish or Chinese (to my knowledge) thus far, I'm proud that I got this far before badly embarrassing myself. :-) Unfortunately, it was before 28 students and I'm sure I'll be the talk of the school this week!