一頭栽到陰溝里

yītóuzāidàoyīngōuli ㄧ ㄊㄡˊ ㄗㄞ ㄉㄠˋ ㄧㄣ ㄍㄡ ˙ㄌㄧ

    • to fail badly and humiliatingly, often unexpectedly

Character by character

Saying俗语俗語

Idiom惯用语 · Rarely used now

Literally
fall head-first into a covered drain
Meaning
To fail badly and humiliatingly, often where it was not expected.

Sources