Dealing with a boss who exhibits childish behavior can be challenging, but it's important to remain professional and not stoop to their level. Try to communicate calmly and assertively, focusing on facts and solutions rather than getting drawn into emotional responses. If the boss resorts to threats or manipulation, document the behavior and consider discussing it with HR or seeking guidance from a higher-level manager. Remember to prioritize your own well-being and mental health in the situation, and don't hesitate to seek support from colleagues or professionals if needed.