I've often wondered how some idioms take off and others fall flat. Why when pigs fly? Why not a cow? raining cats and dogs? Why not tables and chairs? None of it makes sense and yet when we write we can get away with some things and not others. I never can tell what will be a winner.

Other idioms are hit the nail on the head, drunk as a skunk, and out of this world. This was a fun article.