When a negatively charged plastic rod touches a rubber ball, the negative charges on the rod will repel the negative charges on the surface of the ball. As a result, the negative charges on the ball will distribute themselves in a manner that allows for maximum separation, which means they will move as far away from each other as possible within the constraints of the ball's shape. This redistribution of negative charges will typically result in the charges being evenly spread out over the surface of the ball, ensuring as little repulsion between them as possible.
