Urethra Play I Stuck My Little Finger In My Urethra?

I stuck my little finger in my urethra? - urethra play

I've been hit 17 years old and since I masturbate puberty. I recently started playing with my urethra special. It began with the pen tip, but I continued until now, I can put a finger on my erect penis into the second knuckle. Can it be harmful? It's fantastic, and I will not stop, but I do not want to hurt.