The “impossible screw” will “drive you nuts.” It appears to turn only clockwise — even when you turn it around.
It’s a small project you can do in your home shop even if you don’t have a milling machine or lathe. A hacksaw and a file will do. It also makes a nice last minute present.
from Boing Boing https://boingboing.net/2019/01/14/this-screw-is-impossible.html