打小鼓

dǎxiǎogǔ ㄉㄚˇ ㄒㄧㄠˇ ㄍㄨˇ

    • to have one's heart pounding with excitement or fear

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Saying俗语俗語

Idiom惯用语 · Widely known

Literally
beat a small drum
Meaning
To have your heart pounding from excitement or fear, as if a small drum were beating inside you.

Sources