Deliberate misspelling of "casual", meaning casual gamer. Used by some fans of the extremely challenging PS3/XBOX360/PC game Dark Souls, mocking those who have not yet put in the hours necessary to master it, or those relying on walkthrough guides or Let's Play videos. First used by YouTuber OnlyAfro in his "HE'S BACK" video, originating the popular "Giantdad" PvP character build.
What r u, casul? GIANTS, GIANTS, GIANTS, BECOME UNSTOPPABLE.