The scar I remember best is from a knife in my thumb.
It happened on a scout camp trip, where I was carving something with my dagger. The dagger was advertised as being hair-sharp. I found out it was more than that, when it hit a bump in the tree and took a 180 degrees turn, right into the top of my thumb.
I couldn't feel it, it was a clean cut. When I got down to the Samaritan tent, they said: "No reason to stitch this up, might as well just use glue, since it's such a nice cut..."
Before it got glued, I could move the skin and flesh a bit to the side, and actually see the bone underneath. There was hardly any bleeding!
The scar I got from it, is a nice half-circle on my left thumbs upper side.