Two Professors of Mayan studies were having an argument about the apocalyptic Calendar.
'I tell you it's an ancient Mesoamerican fertility calculator,' one of them said, 'a Time-of-the-Month Calendar or neo-Aztec Periodic Table of the bleeding obvious, if you like.'
'Hmm,' the other replied, 'I can see where you're coming from but where's the proof?'
'Just look at those ancient Mayan carvings, the Fertility Goddess' tampon symbols are everywhere; but the calendar stops at 21 December 2012 when the all-powerful Fertility God finally goes down on her during her period, to sate her pleasure at last.'
'And what makes you think that?'
'The inscription says I'll See If I Can Pull A Few Strings.'