Rules Juggler: noun; a participant in a rules-based environment who attempts to juggle the rules or laws of one setting, system or game to gain an advantage within that environment. The use of this method is common in wargaming and role playing games.
Example: In any OD&D game a participant might request that rules of a newer edition of the game be applied to the older rule set. 1. "A result of 18 or higher is a critical hit when attempting a to hit roll isn't it?" 2. "Can we use the 1d6 for each point of constitution for accumulative hit points method?"
I must at this point acknowledge that I referenced the Wikipedia definition of Rules Lawyer when writing this article.