http://arstechnica.com/tech-policy/2012/06/fair-use-gets-stronger-thanks-what-what-in-the-butt/
Creators of What What video sued South Park for making a parody of the video....
They didn't believe that the South Park video was "parody," but rather a slavish re-creation of their work for which they deserve a bit of cash.
Court dismissed lawsuit immediately and accused them of being copyright trolls.