Right-Hand Rule

^(alt-text)

To really expand your mind try some noncartesian porn. Edwin Abbot Abbott has nothing on 'Girls on Girls in Tightly Closed Nonorientable Spaces'.

What If? is now on YouTube!
Check out the first video for the answer to
“What if we aimed the Hubble Telescope at Earth?”
and follow xkcd’s What If? The Video Series channel to be notified about each new video.