The change of direction of the whimmy-diddle's propeller is effected by changing the angle that the stick is rubbed on the notches. Shouting a word is just a distraction to mask the sleight-of-hand.

Of all the Appalachian toys I've read about, the one that comes closest to be considered as a real musical instrument is the limberjack - a jointed wooden doll mounted on a springy stick, that can be made to dance by tapping the stick rhythmically. There is also a soundboard of sorts that is struck by the feet of the doll to produce the noise.