TOILET PAPER

The usage of toilet paper (화장지) is particularly interesting in Korea.
In Korean traditional restaurants, there aren't any napkins on the tables since they wouldn't fit because of the huge amount of side dishes, so there might be some toilet paper rolls hanging from the ceiling.
Furthermore, in toilets it is very likely that it will be forbidden to put the toilet paper in the water after relieving, so you'll have to put them in a trashcan near the toilet.