bit ruiner

In the world of radio show pranks and stunts this is the "hardcore fan" that calls in or more commonly, posts on a fan message board, and explains to the entire listening/viewing audience the "magic" behind the bit. This in turn takes enjoyment away from the intelligent listeners who are able to discern between real and fake. Often the specified "fan" has an inordinant amount of time on his or her hands for research or long-winded diatribes describing any discrepancies in detail. The bit ruiner often sees their show as attempting to gain publicity through dishonest means.

Note: This could also apply to wrestling or other such "in-universe" type real-life based fiction.