“Malarkey” has been a part of American slang at least since the 1920s, and is a name for pretentious, exaggerated, high-flown language that finally adds up to mere nonsense.
The Oxford English Dictionary, whose first published reference for “malarkey” is from 1929, says the origin of the word is unknown.
Its first known user was the cartoonist T A Dorgan, in 1922, but it only began to appear widely at the end of the decade.
A slightly later example is from The Evening Review in Liverpool, Ohio, February 12, 1924:
“Some attempt has been made to account for the defeat of the United States hockey team by the Canadians in the Olympic games by declaring that the result was the fruit of team work rather than individual brilliancy. This is so much malarkey, according to the best informed sources.”
One theory on the word’s origin is that it was a family name. “Malarkey” does exist as an Irish surname, and perhaps the Malarkeys were great and inventive fibbers.
If that is so, then “malarkey” is an eponym, meaning a word formed from proper nouns, especially personal names. For example, “quisling,” which now means a traitor, especially someone who collaborates with an enemy occupation force, comes from the name of Major Vidkun Quisling, a Norwegian army officer and diplomat who collaborated with the Nazi forces occupying Norway during World War II. Another example is “bowdlerize,” which means to censor a book or other creative work, and comes from Dr. Thomas Bowdler, who produced in 1818 what he called “The Family Shakespeare,” from which he had carefully removed those words he deemed unfit for the eyes of women and children.
Some researchers have suggested possible links to the Irish word “mullachan,” meaning a strong boy or a ruffian, or to the modern Greek word “malakia,” which means, among other things, worthlessness.
Whatever the source, people have fun with the word. There’s a board game called Malarky in which players try to separate real answers from, well, malarkey. The Amazon ad says, “In Malarky, you don’t need to know the answers, you just need to make people think you do. A bluffing game that challenges players to invent answers to off-the-wall questions, Malarky is won by the person who tells the most believable bluffs.”
In 1930, Variety could pun on the word: “The song is ended but the Malarkey lingers on.”