鬼知道

guǐzhīdào ㄍㄨㄟˇ ㄓ ㄉㄠˋ

    • nobody knows
    • who the heck knows

Character by character

Saying俗语俗語

Idiom惯用语 · In everyday use

Literally
the ghost knows
Meaning
Nobody knows; said impatiently or dismissively, like 'heaven knows' or 'who the heck knows'.

Sources