"Trolling is a art" is perhaps the definitive statement regarding trolling. If we define trolling as the intentional disruption of another's emotional well being, often through a feigned promotion of an unpopular belief, or political position, the statement is in itself a troll. The deliberate use of "a" where "an" should be is likely to arouse a negative reaction among those concerned with correct english usage. The fact that the statement is itself directly referring to trolling and the art thereof gives further power to its effect; if you're jimmies are rustled by this statement, its author has succeeded, and its veracity has been confirmed.