Technically, it is the creation of worldviews/opinions/fictions where one (or more) deeply beloved aspects of a fiction are combined to create something else that is appealing only to the instigator of the project. Often the results are bizarre and quite possibly insane ramblings.

In a War where histories die quicker then people, and confusion is a weapon, the power of fanwank cannot be underestimated. It is possible that certain factions within the Great Houses are using fanwank to denigrate both the Faction and the Enemy.

see also Create your own entry for the Book of the War....