Have you hugged a Korean today? They do some nice things.
Typically you won't get a Korean insisting you go Dutch. When you go out to eat, it's customary that one person pays the bill; it's assumed the other person will repay the favor if and when the opportunity presents itself. This rule holds true with the exception of when an older and younger person dine together. The older person will treat the younger, and there's no expectation for eventual reciprocation. As it was explained to me, this is because the older person received the same generous treatment from their elders, and they are paying it forward to the next generation, who will pay it forward to the next.
In a similarly unselfish fashion, when fortune smiles upon you, you are supposed to share it with others. On occasions of birthdays, job promotions, marriages, etc. you treat the folks around you. My Korean friend had a birthday a while back, and I asked him how he was going to celebrate. I was expecting that we as his friends would take him out and ply him with drinks and shenanigans, but he had no such rowdy plans. He said he was taking his dad out to lunch and thanking him for making his life possible. Aw.