http://www.animatedknots.com/prusik/index.php

This a mountain climbing knot that was recommended to attempt to eliminate the kink that can develop when using Thingamabobber strike indicators. Now, I have only used them on occassion, but I have not noticed the kink. But, some have and one gentleman recommends using the Prusik Knot above a leader knot. so the Prusik sliding knot has a stop point. The only part not shown here is the loop that extends out away from the knot and mainline must be bigger than the diameter + a bit more. Just slide the end of the pinched loop through the hole the up and over the ball and ease down along the sides of the hole. I have tried this technique and it works. Roll casting and slinging may result in the occassional tangle of fly around bobber, but not an annoying pattern after several hours of use.