[māo shǔ tóng rǔ]   

猫    鼠    同    乳    比喻官吏失职，包庇下属干坏事。也比喻上下狼狈为奸。同“猫鼠同眠”。

汉语四字词语，出自《新唐书·五行志一》，比喻官吏失职，包庇下属干坏事。也比喻上下狼狈为奸。同“猫鼠同眠”。

Thieves and police work together, as the cat and the rat sleep together

猫鼠同处    猫哭老鼠    猫鼠同眠    猫噬鹦鹉    猫鼠同乳