One of the most famous episodes of South Park is called Trapped in the Closet. The episode pokes fun at the beliefs of the Church of Scientology, as well as at two of the most famous scientologists: Tom Cruise and John Travolta. It seems that the episode ruffled some feathers within the Scientology ranks, because some internal documents reveal that the church did a 'classic' investigation of Trey Parker and Matt Stone's lives.
A classic investigation included identifying their friends, performing public records checks and even going through their garbage to come up with incriminating references. Apparently the trash can reveal things like their phone records, bank records, personal letters, what kind of alcohol they drink, any prescriptions, diet and other information.
Apparently, though, what they found is that they're pretty normal guys. The same document said that the commanding officer was 'pissed' that not much was getting done.
(Source)