Where did the phrase "full of malarkey" come from?

The phrase full of malarkey meaning full of nonsense, lies, or foolish talk comes from early 20th century American slang with Irish-American origins. The word malarkey first appeared in American English around 1922, popularized by Thomas Aloysius Dorgan, known as Tad Dorgan, a famous New York cartoonist who coined or spread many slang terms. Malarkey originally meant nonsense or bunk, and is believed to derive from the Irish surname Mullarkey or Malarkey, which was used as a stereotypical Irish name associated with blarney or exaggerated tall tales in Irish-American communities in New York and Boston. The phrase full of malarkey combines full of meaning containing a lot of with malarkey meaning nonsense, similar to full of baloney or full of bunk, which were common expressions in the 1920s and 1930s vaudeville, radio, and newspaper slang. It emerged as a colorful way to accuse someone of talking nonsense or lying without using profanity, making it acceptable for polite society and media. The expression was used in American politics, entertainment, and everyday conversation throughout the 20th century. It gained renewed prominence when President Joe Biden used you're full of malarkey and that's a bunch of malarkey as signature phrases. So full of malarkey is a humorous, non-vulgar American idiom for full of nonsense with roots in Irish-American slang from the 1920s.