I see this mentioned now and then but have no idea how it is done.

i'm pretty sure it is the japanese term for shakey head fishing 

Nice article in Bassmaster this month on the technique.

I like the actual Flick Shake worms, but I throw them old fashioned wacky style - no weight.

It's more of a wacky worm style of finess fishing.  Specialized, weighted hook, specifically designed worms.  Works like a champ, set the hook like you would a drop shot cause the hooks are very sharp and light line is usually employed.  I'm no expert with it but I have caught some good ones with it!!

Thin, finesse worms like the Jackall Flick Shake or Zoom Trick Worm fished wacky style, weightless or on wacky jigs.

Try it by wacky rigging this worm...

http://www.***.com/Jackall_Flick_Shake_Worm/descpage-JFS.html#pImage

...on this jig head

http://www.***.com/Jackall_Weedless_Wacky_Jig_Head_3pk/descpage-JWWJ.html

and make it do this...