I think it is going to be the end of the world, and then I am going to be sad that I didn't kill more people, have more fun and sex up the world just before it ended.
Lemme put it this way. People who believe the world will end on 21/12/12 also probably believe that 3.14 is the entirety of Pi.
Basically, I think the Mayan chronologers got tired of writing out a really long number and figured someone would keep it going for them. However, the Spanish said "LOLNOPE!" before they could hire a new intern to keep writing out the infinite number that is time.
I have last year's calendar in a drawer somewhere. It ends on Dec, 31st of last year. I'm glad we survived the end of the kitty calendar apocalypse. That would've been embarrassing.