This milk has gone bad!
 →이우유 상했잖아!
※ go bad = become rotton or spoiled.
(음식이) 썩다, 상하다.

                〔예문〕
This milk has gone bad! How long has it been in the refrigerator?
이우유 상했잖아! 얼마나 오랫동안 냉장고속에 있었던거야?