One under my left eye which I got during a fight, when I was ten years old against someone older than me. The other kid picked up a rusty pipe and hit me with it. It's really small. The skin merely tore a little from the hit. The pain was from it hitting, not the skin tearing.
One on my elbow from a dog jumping at me (merrily), prompting me to use my arms to block his clawing.
One on my knee from playing soccer, getting tackled and falling on a rock that slightly pierced my kneecap.
Burns on the bottom of my feet from stupidly walking on rock floors hours into their cooking in the Egyptian sun. That was a great vacation. I ran into the pool and I can attest that I heard, or vividly imagined a hiss as my feet rapidly cooled down.
A dent in my thumb for another stupid thing I did. I was fucking around with my knife at night and cut a deep gash vertically into my thumb, about half-an-inch in. It didn't hurt much, so I quickly patched it up with band-aid and sealed the wound with bandages and duct tape. Weeks later, the wound was sealed, no pain was present, and my thumb had a dent in it. Good reminder not to be stupid.
Stretch marks on my stomach, legs and arms. The ones on my arms are actually from working out and quickly growing muscles, as I started doing that when I was 12. The other ones are from being overweight.