Green’s Dictionary of Slang

1. the nickname of a number of relevantly initialled US cities, i.e. Dallas, Texas; Detroit, Michigan; Denver, Colorado.

1946		F. Eikel Jr ‘An Aggie Vocab. of Sl.’ in AS XXI:1 31: big d. n, Dallas.
1961		M. Terry Old Liberty (1962) 165: We took 67 straight in to Big D Dallas, Texas.
1965		B. Jackson Get Your Ass in the Water (1974) 155: I promise you’ll hear / the life of a treacherous bitch, / who sent her friend to hell and made the Big D jail.
1965		J. Thompson Texas by the Tail (1994) 151: Dallas. Big D. The New York of the Southwest.
1967		Current Sl. II:2 5: Big D, n. Denver.
1967		J.L. Hooker ‘Motor City is Burning’ 🎵 Well the Motor City is burning, ain’t a thing in the world that I can do, / Because you know the Big D is burnin’ [etc.].
1970		A. Young Snakes (1971) 86: [of Detroit] Why should I go over there and live like a dog when I can gig anytime I like it here in Big D?
1971		L. Bangs in Psychotic Reactions (1988) 78: Norman Mailer’s Big D was Dallas, and he committed himself to it like a nuthouse.
1987		‘Joe Bob Briggs’ Joe Bob Goes to the Drive-In 1: Banned in Dallas? [...] It was a little too much Powder River for even Big D to handle.
2001		(con. 1964–8) J. Ellroy Cold Six Thousand 3: [of Dallas] A Negro shivved a twenty-one dealer. The dealer lost an eye. The Negro booked to Big D.
2002		D.H. Sterry Chicken (2003) 97: [of Dallas] Anne Frank don’t make me no never mind, as they say in Big D.

2. death.

1977		P. Caputo Rumor of War 258: Death is a pleasure. The Big D is the world’s most powerful narcotic.
1980		‘John le Carré’ Smiley’s People 161: Death, that’s what I’m suffering from [...] the big D.

3. (drugs) LSD.

1969		R.R. Lingeman Drugs from A to Z (1970) 46: Big D, the LSD-25.
2001		ONDCP Street Terms 3: Big D — LSD.