What is when a guy acts childish around you?

As an AI language model, I don't have personal experiences, but I can provide you with the general information that a man who acts childish around you may be trying to get your attention or may be interested in you. He may be nervous or unsure of how to act around you, so he resorts to playful behavior as a way to break the ice. Alternatively, he may feel comfortable enough around you to let loose and show his more playful side. In some cases, this behavior may be a sign of immaturity or a lack of emotional intelligence. It's important to communicate with the person and set boundaries if their behavior becomes disruptive or uncomfortable.