Timothy Wenk's Insomnia

NOTE:  This is used.  In good condition. 
It came from a magician's estate.  
No instructions. 

The magician asks a spectator to cut three 4-foot lengths of rope from an ordinary hank of rope. Two audience volunteers handle the ropes several times, thus assuring the audience that the three ropes are just what they appear to be.
Yes, ordinary, separate, and of equal length. The magician then performs some initial basic magic with the three ropes.

Suddenly the three ropes become transformed into three unequal ropes. The magician then explains that he only made the ropes appear to be unequal. He lets the audience in on the simple 'secret' (don't worry, no real secrets are actually exposed)
No sooner does the audience finish chuckling at how easily it had been deceived, than the ropes are shown to be actually unequal. Yes, unmistakably separate and unequal.
Just as the audience gets over this shock, the three ropes suddenly become equal once again. Yes, unmistakably separate and equal.