Still not entirely convinced this works as I wanted it to but here we go. link to bigger shot on and LCD laptop monitor with circular polariser to cross polarise the cups.
That's pretty cool. Did you try putting anything in the cups, like ice, or would that stop the polarizing effect?
don't know if it would do anything to the polarisation but as it was sitting on my laptops monitor i wasn't to keen on putting anything other than the cups there and definitely no liquids