The article discusses how the ink of a pen can sometimes leak or smudge when the pen is rolled over paper. This issue occurs when the ball at the tip of the pen becomes loose or damaged, causing ink to flow out uncontrollably. This can result in messy and unreadable writing, frustrating the user. To avoid this problem, it is important to check the condition of the pen regularly and replace it if necessary. Taking care of the pen and ensuring that the ball is in good condition will prevent ink leakage and maintain the quality of writing. Therefore, it is important to be mindful of the state of the pen to ensure smooth and clean writing every time.