[1] He graduated from New York Military Academy on a full scholarship and studied English literature and creative writing at Cornell University.
[1] He played Carnegie Hall, the Civic Auditorium, and The Tonight Show – performing with comedian George Carlin, Kenny Rankin, and Lilly Tomlin.
[1] In his 2007 book How the Irish Invented Slang, Cassidy maintains that many common American slang words are of Irish origin, with the word dude for example being derived from "dúid" (meaning "foolish-looking fellow")[4] and snazzy coming from "snasach" (meaning "polished, elegant").
[1] Cassidy proposes that since Irish immigrants were a marginalized group[5] their influence on English would mainly be found in lower-status or colloquial slang expressions,[3] leading them to be overlooked by mainstream dictionaries.
[4] His etymological theories have not stood up to academic scrutiny and are considered factually incorrect[6] and wishful thinking.