铁石心肠刀枪不入
        
            [tiĕ shí xīn cháng dāo qiāng bù rù]
        
        
            'Heart as stone-hard steel, invulnerable to weapons.' Indicates an impervious nature that remains unswayed by external distractions. Those using this nickname often express determination, indifference towards negative comments or difficulties, or sometimes a defensive psychological trait.