My first experience with this was at a baseball stadium. I had installed some gear in the broadcast truck, and was wandering the friendly confines before the game started. Some high school kid came out and was playing catch. I then realized he was the starting pitcher.
Recently, my experiences are with young worship leaders. I've played before with bands of high schoolers doing services for kids, so I've been in bands where I was by far the old guy, but now a couple of the worship leaders I'm working with (for ADULT services) are literally... a third of my age.