시치미를 떼요 · 시치미를 뗐어요 · 시치미 떼지 마
to play dumb; to pretend not to know
Example
동생이 케이크를 먹고도 시치미를 뗐어요.
My little brother ate the cake and then played dumb.
Word parts
시치미 was an owner's name tag on a hunting hawk; removing it hid the real owner.
Good to know
시치미 떼지 마! 'Don't play dumb!' is very common in casual speech.