Meaning: Fake sadness
Originated in: 🇬🇷 Greece
This idiom derives from the ancient idea that crocodiles, despite being ruthless predators, cried when they ate. Depending on who was doing the characterization, the motives for this ranged from luring prey into a false sense of security, to genuine repentance for the kill, to simply feigning morality. Most commonly though the emphasis was on the disingenuousness of it, which is the subject of the modern idiom. The crocodile may shed tears, but he literally just killed and ate the poor creature he’s claiming to mourn. His consequential actions show his heart more than his feigned emotions. The idiom is used to describe someone who is pretending to be sad, but whose actions show that he is not. If he were truly sad, he would not be doing what he is doing.
As mentioned, the idea of crocodiles crying is a very old one which was common in Ancient Greece. However, there is no evidence that the exact phrase “crocodile tears” was used in Ancient Greece. It was instead used as a proverb or a simile. Its use as an idiom is attested to have begun in Greece in the 1st century AD, but the earliest surviving uses are from the end of the millennium, primarily spreading from the Eastern Roman Empire.