saai1 sam1 gei1 ngaai4 ngaan5 fan3嘥心機捱眼訓嘥心机捱眼训

How it's used

This expression combines two distinct idioms to emphasize the futility of an action. It implies that the effort exerted is not only unproductive but also physically draining, often involving staying up late or sacrificing sleep. It is frequently used to warn someone against pursuing a hopeless task or a project that will yield no results.