The magician displays a pair of sticks, with a cord apparently running through them. When the cord is pulled at one end, the opposite end is pulled in, and vice-versa.
the audience is obviously un-impressed, till the two sticks are separated at the top, to show there is no connection between them. Again as you pull one end of the cord, the other end is pulled in, and so on. The audience will soon tell you that the cords pass through the bottom of the sticks, where they are held together. Once again the sticks are separated at the bottom, and you show them both separately, with no connections between them of any sort.
In spite of this, the cords behave as one continuous length of string, with one end reseeding as the other end is pulled out. This is a first rate children’s’ item with excellent comedy potential.