1. Wasting space at a table.
When eating in Korea, the table is covered with food. Main dishes, side dishes, kimchi and, of course, soju.
2. Refusing a drink for any reason.
In Korea, it is accepted and expected that you enjoy spirited libations, heavily, with co-workers. The drink of choice, of course, being soju. There is no negative association with getting absolutely smashed with your coworkers and it is common occurrences at hweshiks (company dinners), which happen frequently. There IS, however, a negative association with refusing to drink with your co-workers, as it makes you seem unfriendly and unwilling to enjoy the culture.