모기 보고 칼 뺀다
mosquito see-AND sword draw-PRES
See a mosquito and draw a sword.
This means to get angry at nothing important
I like googletranslate’s version, though: “Subtract mosquito looking knife.”
In the comic frame below, the phrase at left is a slightly more grammaticalized version of the same proverb (remember, grammatical particles in Korean are often optional), while at the right the character is saying 아까운 내 피를… 넌 죽었다! [my precious blood… you’re dead!].