Today’s BWOTD even makes me laugh when I use it or hear it:
“Oh it’s all just a load of old codswallop”
‘Codswallop’ = Nonsense
This word reputedly dates back to 1872 when an Englishman, Hiram Codd, thought up the idea of putting a marble and a rubber ring in the neck of bottles in order to keep beer ("wallop" in Old English) fizzy. He thought the pressure from the fizz would keep the marble pushed against the ring and thereby seal the bottle. Unfortunately, the thing didn’t work and "codd's wallop" became popular first as a comment about flat beer and eventually as a general term of abuse.
This story however, may itself be a load of old codswallop!