In his absurd work of fake scholarship, How The Irish Invented Slang, the late Daniel Cassidy got it wrong in so many ways. However, none of Cassidy’s claims are more wrong or more absurd than his claims about three related American slang expressions, Hot Dog!, Hot Diggity! and Hot Diggity Dog! While the term hot dog for a sausage in a bun apparently dates back to the 19th century (and apparently derives from the idea that dog meat actually ended up in the sausages!) and these expressions as exclamations of delight or surprise date back to the 1920s, there is some doubt about their origins. I assumed that hot dog was the original version and that it was a minced oath for Holy God, but I suppose that expression would be more common here in Ireland than in the States. Other sources think that young people accustomed to the deliciousness of the hot dog used it as a generic expression for a good thing.
Daniel Cassidy really surpassed himself with his explanations for these expressions. He took an element (from Dinneen’s Dictionary) which is so old-fashioned that it would have been obsolete a thousand years ago, the element –tach, which comes from a verb for to swear. This is an element in ancient and well-established words in Irish, like éitheach meaning ‘lie’ but there were probably still Viking settlements in Ireland when it was last used productively to form such words in the language. He also used another old, literary term for lamentation or groaning, iacht. Thus according to Cassidy, hot diggity dog is árd-iachtach-tach, which The Great Fraud says means ‘a loud oath; a loud declaration; crying out loud!’ Thus anyone trusting Cassidy and believing what he said would think this is a recognised and recognisable exclamation in the Irish language, rather than a ridiculous mash-up of obsolete words and affixes from ancient and medieval Irish thrown together randomly with a fake English definition attached.
Árd-iachtach-tach? Really? This is like taking a word from Chaucer, a word from Anglo-Saxon and a misspelt modern word and combining them without any regard for grammar or usage. This is a perfect example of why this dishonest, idiotic travesty of a book should be publicly burned.