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.
Hokum basically means highly commercial material in a book or film or play, stuff that has been inserted simply because it’s frightening or funny or otherwise entertaining. If a film is described as hokum, it means that it is crowd-pleasing nonsense rather than art.
There is no agreement about where the term comes from. You can find a brief account of the known facts here: https://www.etymonline.com/word/hokum
The usual claim is that it was formed on the basis of bunkum and is perhaps a mixture of that word and hocus-pocus. I had always assumed that this word was something to do with oakum, the picked-out fibres of old ropes used with tar to caulk ships. When I looked on line, I found that this claim is quite common. A man called Walter J. Kingsley, an enthusiastic etymologist (but apparently one with low standards of scholarship), claimed that a Cockney former ship’s captain became manager of the Middlesex Music Hall in London and wherever a show had a weak section, he would recommend plugging it with a bit of (h)oakum. I rather like this story, but it does lack evidence, certainly.
Cassidy claimed that hokum comes from the ‘Irish’ ollchumadh, which he defines as ‘a huge made-up story, a vast invention; fig. a lengthy ad lib or improvisation’. It is true that oll- is a prefix meaning huge or gigantic, while cumadh is the verbal noun of a verb meaning composition or making up. However, ollchumadh is not recorded in any Irish text or dictionary. Cassidy had no evidence that anyone had ever used it to mean anything. It sounds very different from hokum (it is pronounced ollhommoo).
Cassidy says in his book that hokum is first cousin to bunkum, which he derives from buanchumadh. Of course, buanchumadh is a cousin of ollchumadh in a sense, in that it is another word made up by Cassidy for which no evidence exists.