I was really really young, and discovered it by accident. I think I must've been 3 or 4, and nothing came out. It felt good, but then the day after my wang would swell up a lot. It would go down by the next day always. I didn't even know it was masturbating until I got to jr. high in health class when it was discussed. I sort of assumed everyone figured out what felt good on their own time and did it to themselves.