I've always wanted to be able to do that. Never could figure it out. So I learned to juggle, instead. Meanwhile, my friends did that pen-spinning thing. (And, coincidentally, all of my friends who can do it are of asian descent. I'm not one to posit conspiracies of a pen-trick cabal, though, or fallback on slogans like "white guys can't pen-spin".)
So I figured out juggling and other legerdemain, but I never got the pen to spin 'round my thumb. It always wound up several feet away, having bounced off an innocent bystander's knee, and I ended up grinning sheepishly while retrieving it.
At last, there's hope. This tutorial video shows how to do the pen-spinning thing, which I now know is properly called a "Thumb-Around Normal".
And lest you feel smug because you've known how to do the