Wikipedia redirects deejay to disc jockey and states it is "also known as DJ." From the NYT in 2011: "a not-so-green affair with 50 to 80 people at a hot club with an open bar and a hip-hop deejay." The same source , though, uses a different spelling in another article: "after having spent 30 years as an entertainment industry functionary ...

Letter names Each letter of the English alphabet can be spelled as itself (e.g., a DJ or T-shirt) or it can be spelled out using its name (e.g., a deejay or tee-shirt). Vowels still stand for themselves, and while very rare, the plural of vowels are made by adding -es.

Mar 27, 2019 · The Chicago Manual of Style, sixteenth edition (2010) briefly addresses the question of whether the spelled-out form of an initialism or acronym should be initial-capped if the short form is capitalized, at 10.6 Capital versus lowercase for acronyms and initialisms:

get-go; git-go; gitty up noun the very start US, 1966 [First citations:] A clicker from the get-go, the sheet has become must reading for every deejay who sees it. — New Pittsburgh Courier , 19 May 1962 — Stewart L. Tubbs and Sylvia Moss, Human Communication , p. 121, 1974

Nov 1, 2013 · Update (February 26, 2021) Following up on Hugo's notes about the original source of the expression possibly being a Los Angeles–area radio disc jockey, I note that an Elephind newspaper database search turns up five additional instances of "peachy keen" from 1948 and early 1949, all from California (four from the Stanford University student newspaper and one …