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.
The word mug means to attack someone with a view to robbing them. Curiously, the late Daniel Cassidy, in his etymological hoax, How The Irish Invented Slang, does not define the word in this way. To him, to mug someone means “the act of strangling, choking a person” or assaulting someone from behind with a chokehold. This is, to say the least, a rather idiosyncratic definition. When we look at Cassidy’s claim about its origin, all becomes clear.
Cassidy claims that this mug comes from the Irish verb múch, which he claims means to smother; suffocate, choke; press upon, squeeze together; stifle, throttle; destroy; quell, pacify.
The real definitions of the word múch can be found here:
As you will see if you follow the link, this word is more about extinguishing fires than strangling people, which would normally be expressed with the verb tacht.
In fact, the word mug has a clear history in English. By 1818, it is found with the meaning “to beat up,” which derives from a boxing term meaning “to strike the face” and this in turn comes from mug as in a mug you drink from or a face. The meaning of attack to rob is attested by 1846.
As usual, Cassidy’s definition is nonsense.