The line comes from Illidan Stormrage, the antagonist of World of Warcraft expansion The Burning Crusade, released in 2007. Illidan says it in the cinematic trailer while addressing players directly, breaking the fourth wall to challenge them before they enter Outland. The clip spread through gaming forums, machinima and early meme videos, then became a reusable reaction for any underestimated challenge. Its lasting popularity comes from how recognizable the voice and phrasing are, even to players who never fought Illidan themselves.