I prefer to think of this as Missoni-esque rather than clown barf.
I cast on 600 stitches, and knitted through the back loops at the beginning and end of every row leaving a short length of yarn. I then pulled the yarn tightly to create a self-fringe. I did one row only per colour (which took 6-7 yards of yarn).
I ended up doing 82 rows and the scarf is just over 6 inches wide. It grew in blocking and is about 9 ft long, and wraps twice round my neck easily. You could probably go shorter.
I mostly used Sundara Sock Yarn from the second Sundara Scrappy Scarf Swap with a few scraps of FSM, some Koigu and some Violet Green clown barf.