I already have a sworn enemy, and I'm still TECHNICALLY a child.
Stairs.
I was walking down the stairs yesterday (at least, where I am), and I missed a step. I wasn't holding the barrier, since I was carrying things. I slipped, and fell down to the bottom of the steps, from about halfway. I bashed my back, my neck, my tailbone, my ankle, AND my elbow.
It hurts, and I can't get out of bed. Even though I need to.