“Rained harder than a horse tinkling on a ceee-ment slab.”
The phrase is, ‘Rained harder than a COW p*ssin’ on a flat rock!’ ;)
Well, in Wisconsin, anyway! :)
Not pertinent to rain, but my favorite saying is from “The Missouri Breaks” movie, 1976. Rancher is helping a cow with a breech calf giving birth and remarks “Slipperier than snot on a doorknob.”
I watched the movie in a theater in Puente Alto, Chile and roared at that line. The audience turned and looked at me wondering “What’s with the crazy gringo?” The English translation on the screen said “slippery.” That truly was a case of lost in translation.