Gutter oil - Wikipedia
Gutter oil (Chinese: 地沟油; pinyin: dìgōu yóu, or 餿水油; sōushuǐ yóu) is a term used in mainland China, Hong Kong, Macau and Taiwan to describe illicit cooking oil which has been recycled from waste oil collected from sources such as restaurant fryers, grease traps, slaughterhouse waste and sewage from sewer drains.