Apocalypse how: Your guide to handicapping the end of the world
Method of destruction: Elder gods reawaken
How that's going to work: Cthulhu and pals, or some similar antediluvian nightmares beyond human imagining, will awaken and find their way to our plane of reality. A few hundred hours of the most horrific, unimaginable orgy of destruction follow, and then every human being on the planet is rendered into food or slavery. If we're lucky, we'll get some sort of last-ditch stand against the monsters, preferably via giant, Voltron-like armored fighting suits, but let's face it: we won't survive. Those Mayans would have known.
What it's going to look like:
Note: No matter how convincing it sounds when Idris Elba says it, the apocalypse is not being canceled.
Why that probably won't happen: Usually, the awakening of elder gods is portended by strange happenings and dark omens. Since that eagle stealing a baby video turned out to be fake, we can't think of a single thing in the past six weeks that would count. Unless "Gangnam Style" hits a billion views. That would increase the odds by an order of magnitude.
Odds: 500 to 1