风吹草动fēng chuī cǎo dòng

有风吹，草就动。喻指因轻微的动作而发生影响。

例万一有些风吹草动，不要我管门起来，赶得出去，就是个死。——《二刻拍案惊奇》

英the slightest sign of disturbance; at the mere rustle of leaves in the wind; be sensitive to the slightest upset as the grass bends whenever the wind blows;