~은/는/ㄴ 척/첵 하다 (~eun/neun/eun cheo-ka-da/che-ka-da) – acting as if
You can look at this as “pretending to” as well, although I personally prefer “acting as if”.
This grammar expression can be used for action verbs and descriptive verbs/adjectives.
For verbs, attach 는 to both present and past tenses. There is no future tense for this grammar expression.
For descriptive verbs/adjectives, attach 은/ㄴ depending on whether there is an ending consonant (받침).
그 학생은 매일 수업 때 아무것도 모르는 척 했는데 시험을 잘 봤네.
That student acts as if she doesn’t know anything in class but she did well for the test.
우리 강아지는 먹고 싶을 때마다 슬픈 첵 해서 진짜 귀여워.
My puppy acts as if it’s sad every time it wants to eat and it’s really cute.