In gaming, "crunch" refers to the mathematical and statistical properties of choices given a ruleset. The terms is common in role-playing games, as players typically create their own characters (given a broad set of character creation rules).
Some players enjoy powergaming (especially in video game RPGs), often framing their character creation process as a step toward "winning" the game. This results in minmaxing, typically using the most extreme values allowed by the rule set (ie, the boundary conditions). As rule sets are generally imprecisely written, some players view this behavior as exploiting rules loopholes.
See also: Optimization (role-playing games)