Ok, yesterday's Newark-Shanghai experienced a major lavatory problem about 5.5 hours into flight. Captain indicated flight could not continue, and flug would return to Newark. Apparently, some pax who either couldn't wait or did not understand the import of the situation used the toilets anyway, prompting a diversion to Goose Bay. They were on the ground at Goose Bay for some time, then took off again for Newark. They landed at Newark around 4am, and told to remain on the jet while repairs were attempted and jet refueled. Crew of course timed out, and the plane wasn't immediate repairable, so the flight was cancelled around 7am this morning. CO has rebooked pax onto a special section heading to PVG at 8pm tonight (delayed due crew). They gave the pax a rather pathetic 10% off discount cert for the inconvenience.