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.
A capper, in American slang, is a person who caps, who acts as an aggressive shill. In other words, a plant in a rigged gambling game or auction who ups the betting stakes or who drives up the price of the lot. Cassidy claims that these words come from the verb ciapadh, meaning ‘to harass, annoy, torment, goad’, and the noun ciapaire, meaning ‘a goader, a teaser, a vexer’.
In reality, a capper is someone who caps the last person’s bid or bet, raising the price or the stakes. The word makes perfect sense in English and the pronunciation is exactly right, unlike the Irish ciapadh, which sounds more like the English keep.