I think it is Poe's law.
http://rationalwiki.org/wiki/Poe's_Law
Poe's Law: Without a winking smiley or other blatant display of humor, it is utterly impossible to parody a Creationist in such a way that someone won't mistake it for the genuine article.
Poe's Corollary: It is impossible for an act of Fundamentalism to be made that someone won't mistake for a parody.
Poe's paradox: In any fundamentalist group where Poe's Law applies, a paradox exists where any new person (or idea) sufficiently fundamentalist to be accepted by the group is likely to be so ridiculous that they risk being rejected as a parodist (or parody).