And by worst, I mean best.
Opera rap, children's choruses yelling about oppression, Wal-Mart and George Stephanopoulos, and everything else you could never want in a song. It's hysterical.
It was inspired by a poll conducted in the 90's about elements of music that people found least appealing; harp glissandos, political jingoism, spaghetti westerns, oompah bands, etc.
By dropping each of these elements into a blender-of-fucking-awesome, they have created something so bizarre and unpalatable that it's actually an interesting listen. My favorite moment is probably the 20 seconds of weird music followed by 5 seconds of incredibly loud cacophony, followed by a bunch more weird music. You'll know it when you hear it.
If you get really annoyed, I went ahead and mapped out the highlights:
1:23-2:22, 4:07-5:07, 5:43-6:23, 8:35- 9:35, 10:10- 10:48, 12:43-15:30, 17:51-end.
They also created the "best music ever" from the same poll, and I wanted to hurt myself over how bad it was.