On the clothesline tie a few simple loose knots at some distance from each other. This rope with knots wrap around the arm. Holding one end, with his free hand, remove the rope. One has only to put her as the rope uncoiled and nodes on it will be gone.
How to do it? Winding linen cord around your arm, miss its upper end through the nodes. Do it subtly. Removing the collapsed so the rope with knots, take her to the other end, which was held in the nodes. Now if you release the rope, the knots will begin to wag.