A Sudden Clench

Wait, my fingers just twitched! My left hand was frozen in midair like I was about to grab something, and then—snap!—I actually closed it into a fist! The joints bent completely on their own, smooth and fast. I quickly tapped my knuckles against the firm, pale surface right beneath me, feeling the solid, dull thud vibrate straight up my arm. Ha, I'm not stuck at all!