Here's is an interesting story about how Tom Cruise may/may not have threatened to boycott publicity for Mission Impossible 3, a Paramount Pictures film, unless Comedy Central pulled a rerun for Southpark which made fun of Scientology. Comedy Central and Paramount Pictures are both owned by Viacom. Coincidentally, Isaac Hayes, the voice of Chef and also a Scientologist, recently quit the show.
http://www.cnn.com/2006/SHOWBIZ/TV/03/20/leisure.southpark.reut/