toad strangler 

An extremely heavy downpour of rain that can often lead to flash flooding.

That low-hanging Thunderhead Jenkins sure looks like it might produce a real toad strangler this afternoon, so keep your umbrella handy.

toad strangler by Jim from Alabama January 6, 2009

Toad strangler 

A rainstorm so severe that even toads and other amphibious animals would likely drown

It’s supposed to rain today, looks like it’ll be a toad strangler.

Toad strangler by Jester mess March 20, 2022