金屋藏娇

tā kàn lái zhōng hòu lǎo shi jū rán yě huì jīn wū cáng jiāo lìng rén shēn gǎn yà yì

他看来忠厚老实，居然也会金屋藏娇，令人深感讶异。

It is surprising that he, who seems honest and honest, should keep a mistress in a love nest.