HSK 7-9
搞鬼
gǎoguǐ动
to make mischief; to play tricks
账目异常说明有人在搞鬼。
Zhàng mù yì cháng shuō míng yǒu rén zài gǎo guǐ.
The irregular accounts suggest that someone is playing tricks.
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Appears across levels (7-9) in the HSK 3.0 word list.