Local film outfit Brownmark Films and its creators Bobby Ciraldo and Andrew Swant are suing South Park and its proprietors for copyright infringement over their 2008 parody of their music video for the singer Samwell.
This article by the Onion A.V. Club links to both the original video and the parody in question and gets into more legal details. The Brownmark guys are great. I just want to go on record saying that in case they get some of that Viacom money.