Raining dogshit
From Cantonese "落狗屎", when it is raining so hard that the HKO issued an Amber rainstorm warning (but refuses to issue the red warning until 8am) and you cannot not get wet even at all costs.
See:
Raining cats and dogs
Bucket rain
See:
Raining cats and dogs
Bucket rain
Waaaaaaaa diu it's raining dogshit outside how am I even supposed to go home