I wrote about culture of my country. I'm wondering if this is OK with native speakers to understand The things you should keep in mind as a foreign student in a Korean university is that there are a strict seniority and junior relationship among the students in the same department. For example, you always have to answer the seniors with honorifics. The same is true of university clubs. The person who joined the club first becomes your senior. In addition, Korean students often gather together to drink. They often have a custom of having their drink cups pass to their colleagues and have them drink. This seems unsanitary to Westerners. In Korea, however, it is considered an act of ignoring if you don’t take drink cup that he/she gives to you. You do not have to use it if you do not want to use cups that others have just used. If you have enough courage to ignore some unsanitary aspects of it, you can use the cup.