A lady was on a train trying to solve a crossword puzzle. After minutes of difficulty, she turned to the man next to him and said, "Could you please help me on this one word?" The man said, "Sure."

The lady said, "OK. I need a four letter word that ends with IT." The man replied, "What's the clue?" "What is in a bird cage and what the governor is full of." After a few minutes, the man said, "Oh! It must be 'grit'." To which the lady replied, "So it is! Do you have a pencil with an eraser?"