So I just learned about drainage oil....

[simonheros]

First you should read this : 139 Japanese High School Students Sick After Visiting China – chinaSMACK

139 students from Japan visiting China manifest infection symptoms

According to news from Kyodo News on June 18th, after high school students from Ishikawa Prefecture who had recently participated in a school trip to China experienced diarrhea, fever, and other symptoms following their return to their country, the Kanazawa Health Department found in their investigation that there are already 139 people who are exhibiting the aforementioned symptoms. The Health Department believe the students may be suffering from an infectious gastroenteritis.
According to the school, 357 second-year high school students traveled on the 11th to Shanghai, Suzhou, and other places for a 4-day 3-night trip. After returning to their country on the 14th, there were 16 people who did not show up for class the next day, and 16 people who left school early. The school immediately contacted the Kanazawa Health Department. At present, already one student has been determined to have the norovirus, but the infection has not spread to the family of the student or his classmates.
Noun Explanation: The “noroviris” is a nonbacterial virus that causes gastroenteritis. Can be abbreviated as “NV”. The norovirus tends to infect places with relatively high population density and poor sanitation, such as ocean liners. The norovirus is contracted through excrement and saliva. A person may also be infected from eating contaminated shellfish.

Then I looked in the comments....
It seems as if these people weren't used to "drainage oil".
Which leads to the next link...

Link: Discarded Food Waste Slop Recycled Into Cheap Cooking Oil – chinaSMACK

“Sewage oil“, also known as “gutter oil” or “drainage oil”, is the leftover and discarded oil collected from the drains and gutters near restaurants that has been “refined” to be reused and resold as cheap cooking oil. “Slop oil” or “swill oil” is the oil that can also be processed from thrown away food garbage that normally would be fed to pigs. Many street vendors throughout China who cook snacks (especially fried foods) may use “sewage oil” or “slop oil” to save money and keep their costs low.From NetEase:
Why has harmful slop oil once again flooded Wuhan?

(The bold black-hearted boss even guarantees: “Slop oil is safe to eat”). In March of this year, the internet exposed the Wuhan slop oil public health safety incident (refer to relevant report: “My god! Malicious Wuhan oil factories selling slop oil guarantee safe to eat“). The problem attracted heated discussion and criticism from netizens around the country. The problem also very quickly attracted the Wuhan city government’s attention and the relevant department committed additional people and man hours, conducting a city-wide special rectification operation that lasted over a month and investigated a large amount of slop oil (refer to relevant report: “Wuhan emergency seige of slop oil scenes (follow-up report)“). Yet, right when the people feel they can relax, who would have thought that illegal refining of slop oil would stage a comeback, and flood Wuhan.
At the end of September to beginning of October, 《王浩峰聚焦》["Wang Hao Feng Focus"] once again conducted an undercover investigation, witnessing large numbers of hideouts for the illegal refining of slop oil, with the hideouts on one street in the HongShan district being so numerous as to be innumerable; when it comes to refining slop oil, there are no procedures, and whoever offers the highest price is whoever it will be sold to.
This quickly, the problem has resurged. There are city residents who say this is not strange, is common, and is expected. With the supervision of some supervisory departments these days being “a gust of wind”, a problem is exposed, the leadership [government officials] will make some comments, there will be some on-site investigations, but they will see how the wind blows as they investigate and if no one continues asking and no one is after their positions/jobs, the investigations will stop there. Then, they will continue their own (tenured) lives of officialdom. [They will] let the same old problems wait until the next time they are exposed before saying anything. If they are not exposed, [they] won’t say anything.

Oh man.
I feel nauseous.