당랑거철이 · 당랑거철을
a hopeless fight against a far stronger opponent
Example
작은 가게가 대기업과 경쟁하는 건 당랑거철 같아요.
A small shop competing with a big corporation is like a mantis facing a chariot.
Word parts
당 mantis+랑 mantis+거 resist+철 wheel track
Literally 'a praying mantis trying to block a chariot wheel'.
Good to know
Pronounced [당낭거철] — the ㄹ becomes ㄴ after ㅇ.