While it doesn't happen all the time, feather duster syndrome causes the feathers, already curlier than on normal budgies, to keep growing and growing, until they look like the tiny bird-splosions you see here. Obviously, this is in no way beneficial to the bird; they can barely see, can't fly, could very well be deaf, and have the bird version of Down's syndrome. Add a compromised immune system due to the stress of growing out all these feathers, and we have ourselves a birdie that rarely lives for more than a year.
But that hasn't stopped pet shops from selling them, and for a very high price, because look at it.
Luckily (or not) online breeders have provided instructions on how to go about creating your own feather duster, like they're Pokemon or Chocobos. We hope you're up for breeding a new one every six months or so, because remember, they die quick.