3 Words in Running Man Ep. 279(X-Man vs. Running Man Part 2)
When you refuse without any second thought, it is called 단칼에 거절하다 in Korean.
단칼 originally means the single swing of sword. It is used in the descriptions of battle like 단칼에 베다, 단칼로 자르다, etc., meaning cutting with a single swing.
From this meaning, it became to mean figuratively when you do something for once and all. It is used when you act or finish something without any second move. The examples are 단칼에 끝내다(finishing at once), 단칼에 거절하다(refusing without second thought), etc.
그렇게 단칼에 거절당할지 몰랐다.
I didn't know that she would refuse without any second thought.
단칼에 끝내 버릴 수 있는 일을 며칠씩 하고 있는 거야?
Why are you doing the work for days? It should be finished at once!
단칼 is mostly used in adverb from, 단칼에 or 단칼로.
Sometimes, 단칼에 거절하다 is called 단호박 these days. It seems that it is a word play of 단호하다(firm, determined, stern, resolute) and 단호박(sweet pumpkin).
When you are sincere to someone or to your homeland, it is called 일편단심 in Korean.
일(一) means one. 편(片) means piece. 단(丹) means red. 심(心) means mind. It basically means "a piece of red mind". So, it means your sincerity, faithfulness to someone or your nation.
일편단심으로 사랑해 오던 여인에게 오늘 고백합니다.
I will confess to the woman I have loved with sincerity.
Because Koreans should be sincere and faithful to Korea, 일편단심 is added to 애국가, national anthem of Korea. It's in the 3rd verse.
가을 하늘 공활한데, 높고 구름 없이
밝은 달은 우리 가슴 일편단심일세.
Fall sky is wide; high and without cloud
Bright moon like our hearts; it's sincerity.
Because the title of a song by 조용필 was 일편단심 민들레, some people call this sincere mind as 일편단심 민들레.
When nothing will be left, it is called 국물도 없다 in Korean.
It's hard to find why 국물도 없다 is used to nothing will be left. I guess that we promised to eat stew. If you come early, you can eat 건더기(meats, vegetables in stew) and 국물(water in the stew). However, if you are late, you can still drink some 국물. Unfortunately, you cannot eat anything if you are too late. This might be the reason why 국물도 없다 means nothing will be left.
From this meaning, 국물도 없다 means 봐 주지 않는다 or "don't give you any slack" or "I won't give you any second thought." Because of that, someone refused without any second thought. The refused person might think "국물도 없구나."
늦게 오면, 국물도 없어.
If you are late, nothing will be left for you.
별로 늦은 것도 아닌데, 이렇게 국물도 없는 건 너무 하잖아요.
I wasn't late a lot, but you didn't give me nothing. It's too unfair.
More Word: 토씨 하나 안 틀리고
토씨 means 조사(marker, particle) in Korean. You can learn what it exactly means here.