Apocalypse babies will be the resulting offspring off all the people who believe that the world will end in 2012 and have end of the world sex. For people who want to be with their loved one "one last time" or just a reason to get laid. And who needs protection when the world is going to end?
Or they have sex celebrating the fact that the world did not, in fact, end, and end up having babies anyways.
So this guy keeps trying to get into my pants saying that it's 'the end of the world'. Ain't no way I'm having his Apocalypse Baby!
Guy 1: Man chicks put out when they think they are going to die!
Guy 2: Careful man, your gonna have like 5 apocalypse babies!
Guy 1: Then let's hope the world actually ends, eh?