瞎猫碰上死耗子

xiā māo pèng shàng sǐ hào zi

a blind cat finds a dead mouse (idiom)

blind luck

xiā

blind

māo

cat (CL:隻|只[zhi1])

pèng

old variant of 碰[peng4]

shàng

(bound form) up; upper; above; previous

to die

hào

to waste

zi

noun suffix, as in 椅子[yi3 zi5] "chair"