yī lì lǎo shǔ shǐ huài le yī guō zhōu
lit. a piece of rat feces spoiled the whole pot of congee (idiom)
fig. one bad apple can spoil the whole bunch
yī guō zhōu
(lit.) a pot of porridge
(fig.) a complete mess
yī kē lǎo shǔ shǐ huài le yī guō zhōu
see 一粒老鼠屎壞了一鍋粥|一粒老鼠屎坏了一锅粥[yi1 li4 lao3 shu3 shi3 huai4 le5 yi1 guo1 zhou1]