Dictionaries say it means “nonsense,” but most are uncertain of its origin. Some etymologists tell of a 19th Century British inventor named Hiram Codd, who created a soda bottle with a glass ball in its neck. The pressure of the bubbly contents forced the ball against the neck, providing a built-in stopper that you pushed in to pour. It was a successful invention (though kids kept stealing and breaking open bottles to get the “marbles” inside).
Nineteenth Century denizens of the pubs, who used “wallop” as slang for beer, sneered at these fizzy, sweet drinks, calling them “Codd’s wallop.” The derogatory term grew to become an expletive for something silly and useless – nonsense.
Some etymologists dispute this derivation, claiming the story itself is codswallop, but they can offer little better.Readers of this essay may consider it, too, to be codswallop. However, we live in a world full of codswallop, so why not just a little bit more?