Huh, here I figured it had something to do with the fluting you find on the handles of most screwdrivers, but this was even cooler. Favorited for his related home projects.
He is my favorite real-life mad scientist. Check out his hundreds of videos in which he completely deadpans explanations of how (and sometimes why) he put induction-powered LEDs on his eyeballs, or how he discovered that carbon dioxide is acetone-soluble at extreme pressures. His current obsession appears to be working with anhydrous ammonia, which is to say gaseous ammonia cryogenically chilled until it's a liquid that does all sorts of scary things (like turning hardwood temporarily malleable).