鸡同鸭讲 (jī tóng yā jiǎng)

Literally: A chicken talking to a duck

Example: “我们说的不是同一件事，简直是鸡同鸭讲。” — We weren't talking about the same thing; we were completely at cross purposes.

English equivalent: At cross purposes

Origin: Genuinely Cantonese in origin rather than classical Chinese, first circulating as everyday spoken slang in Guangdong and Hong Kong before entering wider written Mandarin use. The fuller original folk saying runs "鸡同鸭讲，眼碌碌" — a chicken talking to a duck, eyes just rolling blankly — popularized further by its use as a memorable lyric in the long-running Cantonese television series Virtues of Harmony. The image needs no elaborate explanation: a chicken's clucks and a duck's quacks are different enough that neither bird could possibly understand what the other is communicating, making the pairing an intuitive, everyday stand-in for any conversation where two people are, in effect, speaking completely past each other.