亮红灯

Traditional (Taiwan): 亮紅燈

liànghóngdēng ㄌㄧㄤˋ ㄏㄨㄥˊ ㄉㄥ

    • to refuse approval
    • to block something

Character by character

Saying俗语俗語

Idiom惯用语 · In everyday use

Literally
show a red light
Meaning
To refuse approval or block something, like a red traffic light telling it to stop.

Sources