Dead Men Tell No Tales

The monkey tries to win the argument with the fox by pointing to the cemetery. But the fox is clever and doesn't believe him. He says, lie to your heart's content, meaning lie as much as you want. An impostor is a pretender, someone's pretending to be something that they're not. Those kind of men boast loudly when no one is there to expose them. So liars will lie when no one else is around to tell the trut.