have underhand secret dealings
Private giving and receiving, Chinese idiom, Pinyin is s ī Xi ā ngsh ò ush ò u, which means giving and receiving not openly. From Qian Qianyi's collection of Mu Zhai Chu Xue and Jiang Ming Fu's discussion on the issue of priority and exemption in Qing Dynasty
The origin of Idioms
Qian Qianyi of the Qing Dynasty wrote in the collection of Mu Zhai's early learning and the discussion on the issue of preferential immunity with Jiang Ming's family: "Kuang Zhuangtian was once in Xining, but now he is back in Yangwu. He was granted by Guoqin, and he dares to give and receive it privately."
Idiom usage
Although one is willing to sell, the other is willing to buy, but the mainland non concession is comparable, Chinese businessmen and foreign businessmen can never ~. (Chapter 52 of Li Baojia's officialdom in the Qing Dynasty)
have underhand secret dealings
take both public and private interests into account - gōng sī jiān gù