The expression to cry "crocodile tears" means a false display of emotion or insincerity. It is actually derived from crocodiles appearing to weep while eating their prey. This is because as they chew, the air gets pushed through their sinuses into their tear ducts and leaks from their eyes, making it look like they're actually crying. Crocodiles' eyes water because of the hisses and huffs during feeding, but not with remorse. And that's where we got the notion of crocodile tears from.