Gee-haw whammy diddle

A gee-haw whammy diddle is a mechanical toy consisting of two wooden sticks.

One has a series of notches cut transversely along its side and a smaller wooden stick or a propeller attached to the end with a nail or pin.

The operator may do this surreptitiously and yell "gee" or "haw" to make it appear that the propeller is reacting to the commands.

The nail holding the propeller must pass through a hole of approximately twice its diameter, essentially a twirling hoop on a stick.

To observe the effect, the propeller attached to the end of the ribbed stick must not be pinned at its exact centre of mass, i.e. off-center or loose.

is some unknown scaling factor that characterizes the force with which the two sticks are pressed against one another.

By rubbing a finger against these grooves on the side, one can also introduce a horizontal alternating driving force

is a phase shift (describing the lag time between when the grooves contacts the moving rod, and finger respectively) and, again, X is some unknown scaling factor.