My very first scar came from when I ran into the garage to find something, tripped, and impaled my hand on an enormous screw. It didn't go all the way through my hand, but you could see the top of my hand poking up like a tent. SICK.
After that I remained mostly scar-free until I got to Market Basket and sliced open my thumb with my box cutter. That sucked, but it allowed me to go home early.
Just as recently as this summer I got two scars doing the same thing - Acting. In a Friday the 13th fanfilm I acted in, I was required to fall on my ass on my way through the woods, which resulted in a tree branch slicing up my waist area, and then a few minutes later, I get tripped and fall into a hole, which was cool except for the enormous rock covered in dirt that nobody but my shins saw.
Here's a video of me scarring myself in this film. Around 1:07 you see my do my stomach, and then at 2:07 I fall into the hole and whack my shin. It's not worth watching beyond that, since the film is pretty lame:
Jam it back in, in the dark.