3 Words in Running Man Ep. 283(FC 런닝맨 in 상해, FC Running Man in Shanghai)
역사 is history. Then, what is 흑역사? 흑 here means dark or black.
In the history of some person, nation, product, etc., there is some embarrassing or painful period that you want to cross it out with buckets of black ink. It is called 흑역사.
여기서 일했던 시절은 내 인생에서 완전 흑역사였어.
The period I worked here was most painful and embarrassing in my life.
애플 같은 기업도 흑역사가 있을까 싶었는데, 있긴 있더라고.
I once thought that the companies like Apple would never have any shameful history, but they had.
This word is not in the dictionary. So, you shouldn't use this word for official documents or some situation that you should be polite.
When a person goes through some hardship which they didn't have to, it is called 사서 고생.
It came from the saying, 고생을 사서 한다, buying and going through hardships.
Generally speaking, no one buys hardship. Everyone buys solution to the problems. It means that you figuratively bought some trouble because of your wrong deeds or action.
왜 그렇게 사서 고생을 해?
Why are you going through such a good-for-nothing trouble?
사서 고생하지 말고 내가 하자는 대로 해 봐.
Don't waste your time with fruitless trouble, and do what I say.
In some games, competitions, wars, someone alone works hard and others don't. It seems that the person is only playing, competing or fighting and others are not there. It is called 고군분투.
고(孤) means lonely or alone. 군(軍) means army or soldier. 분(奮) means show off and 투(鬪) means to fight. So, it means "lone fight by a single soldier".
고군분투 끝에 성공했다.
He succeeded after a long and lone fight.
고군분투하고 있는 그 선수가 무척 불쌍해 보였다.
I felt sorry for the athlete who seemed to be competing alone.