BIG BANG BLACKOUT

I've been hearing this term around lj but still don't know what it means. Can someone explain this to me?

COMING 23 FEBRUARY TO bigbangblackout

EDIT: In my heart of hearts I suspect it is a slash-a-thon, but still don't know what the term big bang (yes I know what the big bang theory of the universe - just not sure what it means on lj)