Can get soo small, normally it's a bit bigger:

I was 13 and on holidays with my parents. They went for a walk, and I stayed at the apartment. I felt an erection of my dick (then tiny, about 8 cm or 3 1/2 inches erect) and took it out of my pants. I started moving my foreskin forth and back a little bit (I coudn't pull it back completely till I was 19). That felt good, and after some time I had a new and pleasant sensation, and a few milky drops fell on the floor. I had to hurry to clean eyerything up before my parents came home.
That was the first time I realised cumming. I had had some erections before, but never masturbated.