没心没肺假先森
[méi xīn méi fèi jiă xiān sēn]
'Heartless, lung-less, False Mister' playfully describes a character who doesn't let things get under their skin, acting carefree and indifferent while presenting themself falsely. Here, 先生 (xian sheng) usually refers to 'mister,' but '假先森' adds the prefix 假 meaning 'fake,' humorously describing someone feigning seriousness.