I was curious as to what it meant. I looked it up and found it on the urban dictionary. According to that, "old head" means either 1) "someone who has been in the scene before you or your group, or 2) someone who is still in the scene beyond the acceptable or expected age." I am guessing the teenager was using the second definition. Of course, that must mean I look old, which then means I must have an old head. I wonder if my balding head with gray hair helps me look like an old head.
At first I was confused about why they were calling me that. I didn't ask, because I have been called many things. As I ponder this definition and the person's tone of voice, "old head" is not disrespectful. It might sound that way. Yet, there is even a sense of amazement that one is still on the scene; in my case, they must have been amazed that I was still playing basketball and hanging out at a basketball court. That's not a bad thing, as long as they let this "old head" play.
So beware, before you jump to conclusions when somebody says something about you, make sure you understand what they mean. Many of the problems we face in life centers on poor communication. We get angry and frustrated with people when our communication falters. Not understanding a person's word choice often creates much of our problems. In the words of James,"Be quick to listen, slow to speak, and slow to angry." Thus, as we apply this verse to life, we might be surprised by what people are saying.