Ninja cut

I have a cut in my left thumb, that I really don't know how it got there.

I just noticed it this morning, and it makes me wonder, how long has it been there? What did I cut myself with? What was I doing? Why didn't it hurt? Why does it hurt now that I know it's there?

I find it very interesting how the human brain works that way. It's a totally superficial cut, but the exact moment you notice it's there, it starts to hurt. I've had that happen when I notice blood coming out of a cut or a scrape I didn't know I have. I once woke up to find out my left arm all covered in dried up blood, wtf? What could have made me bleed that much but at the same time not cause any pain? It freaked me out for a bit. Stupid brain.

Moving on...