nonsensical talk or writing
Senseless talk or writing; nonsense; rubbish.
Used to express disbelief: nonsense!; rubbish!
The origin of "codswallop" is unknown, though it was already in general use by the time a 1959 British TV show featured it. While a 2006 search failed to find earlier references, the phrase may have existed before then, as a fictional character named Sir Aubrey Codswallop appeared in a 1947 newspaper column.