If you teach your students about countries and nationalities, English for Academic Purposes courses or you are doing business courses have a look in the Faux pas section on Wikipedia. It gives you a summary of culturally accepted norms around the world.
The term originally comes from France, and it literally means ”false step”. This expression is usually used in social and diplomatic contexts.
You can use the faux pas information during your speaking classes or even grammar classes when you are doing comparing and contrasting adjectives. When you teach business classes it could be a very real life discussion class, where your students exchange their experiences from business trips. During your EAP course you can help students learn more about the country they are going to study in.