Cut pieces of yarn that are twice as long as you want your falls to be. When you fold each piece in half, it will make two dreads. You'll need at least 30 to 40 strands of yarn for each ponytail fall, so make sure you look at the yardage on the label and buy enough.
Fold each strand of yarn in half in the middle so that you have two strands of equal length hanging down. Contemplate how much it would rock if dreading your real hair was this easy.
Stick the folded middle portion of the strand a couple of inches through a ponytail band. You may want to use slightly bigger hair bands than you normally use, since you're really going to pack them with yarn and you still need to be able to fit your real ponytails through.
Pull the two ends of the strand of yarn through the looped middle section to make a knot, then pull down on the ends to snug the knot up against the rubber band. Voila! Two dreadlocks.
Continue to fill the band with the yarn, placing the knots side by side. When you're done, the bottom half of your hair band should be completely full of yarn.
Use the ponytail holder just like you would one that didn't have yarn on it. In other words, pull your real hair through the band, twist the band and double it around on your hair. Fluff out the yarn all the way around your ponytail to hide it and go rock your cyber goth dreads!