The Chinese idiom "尔虞我诈" is formed from four characters: "尔" meaning "you", "虞" meaning "to deceive", "我" meaning "I", and "诈" meaning "to cheat". It originates from the historical text "Zuo Zhuan", where it describes a scenario of mutual suspicion and dishonesty between two parties. The phrase pairs "尔虞" (you deceive) and "我诈" (I cheat) in a parallel structure to convey reciprocal deception.