For some time now, some of my on-line friends have advised me to provide a version of CassidySlangScam without the invective aimed at Cassidy and his supporters. In response to that advice, I am working on providing a glossary of the terms in Cassidy’s ludicrous book How The Irish Invented Slang with a short, simple and business-like explanation of why Cassidy’s version is wrong.
This is one of earliest manifestations of a family of minced oaths based on ‘Jesus’. This, in the form of Gee Whilikens, is found from the 1850s and is originally associated with south-east England.
Cassidy ignores these facts and claims that it comes from the ‘Irish’ phrase Dia Thoilleachas, which he claims is an exclamation meaning ‘God’s Will!’ There is a word toileachas (with one l), which is given as meaning will in Dinneen’s dictionary, though it is not in Ó Dónaill. It is also found in Scottish Gaelic. So Dia exists and toileachas exists. Could the phrase Dia Thoileachas exist with the meaning God’s Will?
No. There is absolutely no evidence for the existence of this phrase, and it makes no sense in terms of Irish grammar. The Irish for God’s Will is ‘toil Dé’. You could, presumably, say ‘toileachas Dé’ (though the word toileachas is uncommon and obscure), but how would that give Gee Whillickers rather than Whillickers Gee?