Per Wikipedia: (I had to look it up) Crocodile tears is false or insincere weeping, a hypocritical display of emotions. The expression comes from an ancient anecdote that crocodiles weep in order to lure their prey, or that they cry for the victims they are eating. They are fake tears.
An alternate explanation for the expression's origin is that crocodile tears cannot be authentic because crocodiles cannot cry; they lack tear ducts. Yet this is a myth: Crocodiles possess lachrymal glands which secrete a proteinaceous fluid, just like in humans, though tears will only be visible after a crocodile is out of the water for a prolonged period of time, and dries out. However, while crocodiles can and do generate tears, they do not weep or cry for remorse.[1]
In Esperanto culture, krokodili ("to crocodile") has come to mean "to talk in another language where the situation begs Esperanto", the allegory being that Esperanto speakers who lament its lack of use while not using it themselves are like crocodiles weeping over their victims.
The expression was used by Shakespeare in Othello Act 4 Scene 1
