Another oft-quoted piece of Cassidese is the phrase béal ónna. According to Cassidy, béal ónna is the origin of the American slang word baloney, meaning nonsense or rubbish.
Béal ónna (pron. bæl óna), silly loquacity, foolish talk; blather; blarney; stupid gossip.
There are two major points we need to be clear on here. First of all, the Irish phrase béal ónna is not an Irish phrase. It does not exist. It is composed of two words: béal, which is very common and means mouth, and ónna, which is so uncommon and obscure that it doesn’t even get a mention in Ó Dónaill’s 1300 page dictionary of Modern Irish. Before Cassidy, nobody had ever linked it to béal to make a phrase béal ónna. If you used the phrase among Irish speakers they would look at you in confusion and wonder what you were talking about. It is pure invention from a total fantasist.
Look it up on Google! You will find no references to the phrase on line apart from direct quotes from Cassidy. The only other example I came up with was on a forum, where it was used casually to mean nonsense by someone whose username was Dancas1 – obviously Daniel Cassidy the great fantasist himself!
Secondly, baloney is an example of an interesting linguistic phenomenon called the minced oath. This is quite common, and exists in many languages. A minced oath is simply where an obscene or blasphemous or unpleasant word is disguised by cutting bits off it, or by saying a word which sounds a bit like it.
Thus the French avoid saying Sacré Dieu (Holy God) by saying Sacré Bleu (Holy Blue). The Irish say dar fia (by deer) instead of dar Dia (by God) or daingniú air (strengthening on it) instead of damnú air (damnation on it). The English say things like Gee Whizz (Jesus) and Blimey (God Blind Me) or Sugar (shit).
It isn’t a difficult concept. It explains terms like Baloney, which is a minced oath for balls or bollocks. It also explains phrases like Holy Moly or Holy Mackerel and a number of other minced oaths for which Cassidy proposed ridiculously improbable Irish meanings.
There are many naïve and silly people out there who have looked at Cassidy’s claims and asked the question, how did scholars miss these obvious Irish derivations? If you stop to think about it, the answer is pretty clear. There have been lots of clever Irish people who spoke Irish and English and if these phrases were really so obvious, they would have been spotted and suggested before.
The reason why scholars didn’t spot them is simply because most of them were invented by Cassidy and don’t exist! Occam’s Razor, my arse!