I caught you red-handed!
→   딱걸렸어.

[예문]
catch (someone) red-handed : 현행범으로 붙잡다.

A : Why are those students standing around like that?
     Why aren't they in class?
    저 학생들은 왜 저거고 서 있지? 교실에 안 들어가고.

B : They were all caught red-handed cheating on an exam.
   시험 시간에 단체로 커닝하다가 덜미를 잡혔대.