Tā zhēnshì dǎndà-bāotiān, jìnggǎn tōu jǐngchá de chē.
He's truly audacious - he actually dared to steal a police car.
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Literally 'gallbladder big enough to wrap up the sky' - Chinese tradition locates courage in the 胆 (gallbladder), so a sky-sized one means fearless to the point of recklessness. Usually carries a critical or sarcastic tone.
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Strong negative connotation - accuses someone of being foolhardy or insolent, not bravely heroic. For positive courage, use 勇敢 or 英勇 instead.