"Gangster" Soy Sauce Hot in Southern Taiwan The Taiwanese idiom "a black bottle filled with soy sauce" is an expression of surprise at something unclear or unfathomable. You may also feel a sense of surprise about the soy sauce made way down south at Pingtung Prison.
台語俗諺「黑矸裝豆油」，比喻「看不出來」、「真不簡單」的訝異之情，不過位處國境之南的屏東監獄，卻是「黑道做豆油」，同樣令人驚嘆不已。