No matter how you spell or say it, the “Kook” or “Cookie” is a curious-looking “old school” lighting trick that has its roots in Theatre, Opera & Still Photography.  Basically it’s a device consisting of a thin plywood (or Masonite) board covered with a variety of random organic “cut out” shapes.  Placed near the front of a Movie Light, the Cookie is used for casting shadows of organic-looking “patterns” or silhouettes in order to “soften” a light source.  (Also see Brancholoris and Gobo.)