EFFECT:
Show 2 ropes, 2 rings and 1 stick. Put 2 ropes at the center of the stick, tie a knot and put 2 rings round the 2 ropes on theeither side separately and use the 2 rings and the stick to 2 tie a knot. Say 1,2,3 and draw out the stick, the rings will magically come off and the knot will have disappeared.