顶门杠

Traditional (Taiwan): 頂門槓

dǐngméngàng ㄉㄧㄥˇ ㄇㄣˊ ㄍㄤˋ

    • person who obstructs and blocks a matter from going smoothly

Character by character

Saying俗语俗語

Idiom惯用语 · Rarely used now

Literally
the bar that braces the door
Meaning
A person who obstructs and blocks a matter from going smoothly. Critical.

Sources