@BillGates: Tons of interest in reinventing the toilet. How much do you know about #toilets? Take @gatesfoundation quiz: http://t.co/QVRdmdKB

Tons of interest in reinventing the toilet. How much do you know about #toilets? Take @gatesfoundation quiz: http://t.co/QVRdmdKB http://twitter.com/BillGates/status/238396752019992576