Idiom 140: Shape up

상황: 어떠한 상태에서 더 나은 상태로 나아가기를 시작할 때를 나타내는 표현입니다.
형태를 이루다, 구체화하다, 발전하다

shape up = begin to act and look right

The school boy was hitting other children and talking out in class. He was told by the teacher that he better shape up or he will have to stand in the hallway.