It is widely believed that the expression "kekeke" comes from Korean players of StarCraft. It is an onomonopoetic Korean phrase similar to the English "hahaha", Spanish "jajaja" or Japanese "huhuhu", and is meant to express laughter. It is often used in-game as an expression of exhultation or as a form of mockery. Commonly, it is associated with a simple Starcraft tactic that involves massing a large number of units and using them to rush an enemy base before an opponent is sufficiently prepared to defend. This is often called a Zerg Rush, after the Starcraft faction for whom the tactic was created. The phrase "OMG Zerg Rush! kekeke!!" is sometimes used outside of the game to indicate any form of overwhelming or swarming force.Link (via Kottke)
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.