Don't let the quiet fool you — she's secretly wild.
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Colloquial, usually playful rather than insulting. Describes an MBTI-style gap between public calm and private intensity, often used for introverts who reveal a party-animal side in private.
mistakes
The 闷 here is read mēn (stuffy / bottled-up), not mèn (depressed). Getting the tone wrong sounds off to native speakers.
