"IT'S RAINING CATS AND DOGS!"
I have no idea where this expression came from or how it started but I've heard it all of my life. Am sure that it stunned a lot of little kids and made them go outside to see if it really was raining cats and dogs!
Yesterday where I live the rain was coming down in torrents. Really bad storm with high wind as well.
Only cat and dog I saw were my own and luckily for them, they were inside. And so was I.
Every year when I taught school [second grade,] I'd ask my students about this expression: They all knew it but a lot always questioned it. Best thing I did was to explain that it meant it was really pouring the rain. And I'd have them draw a picture of cats and dogs falling in the rain. Those pictures were hilarious: Kept a lot of them for years.
If you hear the expression "It's raining cats and dogs" and don't know what that means, I hope you do now. And no need to look outside for the real things. They won't be there.