The phrase sounds like the word “harmony” in Mandarin, it refers to government censorship. It is widely used as a verb. Instead of saying something is censored, it is said to be “river-crabbed”. The Chinese have also created cartoon memes
and songs about the grass-mud horses’ fight against the river crabs that threaten the horses’ habitat called Mahler Gobi. Mahler Gobi is a homophone for another Mandarin curse word meaning “your mother’s f---ing c---”.