What do you call a white, foamy, foul-smelling goo that randomly spews from the ground and is quickly pushed back into the gutter by firemen? Hint: it looks a bit like a mix of “bird [poop] and Bisquick”.
US comedian Jon Stewart - arguably Chinese netizens’ favourite foreign funny guy - didn't have an actual answer, but he recently brought America’s attention to the strange occurrence in Nanjing, in eastern China’s Jiangsu province, on his late-night satire programme The Daily Show.
His comedy bit comes from photos that emerged last week of a mysterious white slurry that had oozed out of a street  in downtown Nanjing.
The foam, which some described as “marshmallow-like”, spread to a radius of 45 metres in the middle of Wende Road and released a putrid smell. Firefighters arrived and swept the foamy substance into roadside drains.
City authorities didn't have definitive answers either of what the substance was or where it came from, but they said it was "caused by subway construction underground".
“Things may be bad, but at least our streets don’t burp mystery goo,” the satirist said on the segment, joking that Nancy Drew and the Mystery Ooze of Nanjing would probably be the most disgusting of the detective series.
Stewart also took shots at China’s environmental problems, saying only a small “sweet spot of air” was left between the knee-high white goo and infamous air pollution.
But the real punch came when Stewart said the mystery substance was made of “corn starch and Foxconn workers' tears”. Some members of the audience were left somewhat aghast, China blog Beijing Cream pointed out .
He ended the segment by taking a snub at a similar case in the United States, where mysterious black dust and chunks were found scattered across roads. The dust turned out to be petrolium coke from tar sands oil refineries.
Stewart's The Daily Show has become extremely popular on the mainland in recent years, with online videos racking up millions of views each. Clips with Chinese subtitles are often found scattered across the internet.