greaser
noun [ C ] old-fashioned slang uk/ˈɡriː.sər/ us/ˈɡriː.sɚ/
油头飞车党（留长发，骑摩托，穿黑色皮衣的一伙人）
a man with long hair who rides a motorcycle, wears black leather clothes, and is often a member of a gang
Greasers were originally called that because of the grease that they used on their hair and on their bikes. “油头飞车党”的称呼源于他们在车和头上都抹油。