mistakenly cursed

I tutor ESL students. I enjoy it. I was trying to convince my students that they needed to write in their journals more frequently. The majority of them protested because it was too hard for them to write in English. I made a deal with them. I’d learn a phrase in each of their languages (Chinese, Spanish and Urdu) if they promised to continue to write in their journals. They agreed. One of the students decided that he was going to teach me how to say “hi” in Chinese. It wasn’t his native language. He said, “po cai!” My Chinese students began to laugh wildly. I asked why it was so funny. The student who said it looked puzzled. A meek female student explained, Miss….he said F*ck You!