百毒不侵其实是麻木至极刀枪不入其实是遍体鳞伤
[băi dú bù qīn qí shí shì má mù zhì jí dāo qiāng bù rù qí shí shì biàn tĭ lín shāng]
'Being impervious to all poisons is actually extreme numbness; impenetrable by spears is actually full-body injury' conveys the appearance of not caring, while actually being hurt deeply inside, expressing self-protection from constant pains by developing emotional numbing as a defensive mechanism.