Magic Professor's Nightmare Rope Routine Trick
Effect: you show three pieces of rope, each a different length. You gather up the ends, and by hanging them in different positions, state that you have now made them look equal in length. But pulling them apart - they are unequal, you then commence to pull on the ropes until you "stretch" them and show quite clearly that the three ropes are now equal in length. You then return them to their original state.