My Korean coworkers keep inviting me to hoesik and I never know what to expect?

Hoesik (회식) is basically a company team dinner, and it is a big part of work culture here, though it has gotten lighter in recent years. The classic pattern is rounds, called 차수. The 1차 is dinner with lots of grilled meat and soju or beer, the 2차 might be a hof or pub, and the 3차 sometimes ends up at noraebang for karaoke.

A few unwritten rules help you fit in. Pour drinks for others rather than yourself, hold the bottle with two hands when pouring for someone senior, and turn slightly away when you drink in front of the boss. Wait for the most senior person to start eating or to raise the first toast. You really do not have to drink heavily anymore, and saying you are driving or that you cannot drink much is widely accepted now, so ordering a soft drink is totally fine. Can you say no? Sometimes yes, especially with a genuine reason like a prior plan or family, but skipping every single one can read as a bit distant, so a good middle path is to show up for the 1차 and quietly slip out afterward. The upside is the company almost always pays, and a lot of real relationship-building happens there, so it is worth going now and then even if you are not a big drinker.