Green’s Dictionary of Slang

1. a very hard blow, literal or fig. use.

1944		Time 12 June 11: The President then quietly dropped his blockbuster.
1956		I. Shulman Good Deeds Must Be Punished 78: He caught Murray high on the side of his head before Murray’s blockbuster dropped him.
1962		(con. 1940s) G. Mandel Wax Boom 250: Another blockbuster had turned part of the canal into a lake.
1962		J. Quirk No Red Ribbons (1968) 288: In February, 1959, Three threw a block-buster at Paul.

2. anything enormous, gigantic; often used of a best-selling novel, film, TV series etc; also attrib.

1943		Ladies’ Home Journal Nov. 116: The day was an emotional block buster for them all.
1947		(con. 1944) J.H. Burns Gallery (1948) 47: There was also the largest woman in captivity [...] We called her Blockbuster.
1947		S.J. Perelman ‘Take Two Parts Sand, One Part Girl’ in Keep It Crisp 90: It’s poetic and yet it’s timely too! It’s a blockbuster, V.J.!
1959		J. Blake letter 15 Oct. in Joint (1972) 147: Aside from these blockbusters.
1964		H.S. Thompson letter 28 Jan. in Proud Highway (1997) 433: It will not be a blockbuster, but it might be coherent.
1973		G.V. Higgins Digger’s Game (1981) 114: This could be a blockbuster operation.
1987		‘Joe Bob Briggs’ Joe Bob Goes to the Drive-In 98: We have a blockbuster holiday flick, exclusively playing on the outdoor screen.
1999		Guardian Rev. 25 June 12: I have never been one for easy summer reads of the blockbuster variety. [Ibid.] 29: t’s generally perceived as a celluloid blockbuster-to-be.
2000		Guardian Guide 29 Jan.–4 Feb. 8: A profitable summer blockbuster.

3. an intoxicating drink.

1945

Omaha World-Herald 30 Dec. 3: Blockbuster [an intoxicating drink].

4. (drugs) barbiturates.

1967		Altman & Ziporyn Born to Raise Hell in Lingeman (1969) n.p.: We had some blockbusters (white barbiturate pills with a yellow stripe [Nembutal]).
1981		D.E. Miller Bk of Jargon 336: blockbusters: Barbiturate pills, possibly Nembutal.
2001		ONDCP Street Terms 3: Block busters — Depressants.

5. (US) an outsize, ultra-powerful firecracker.

2001

A. Schulman 23rd Precinct 136: The four cops walk to their cars just as a blockbuster goes off down the block. Two times the size of a M-80 firecracker, its power is equivalent to a quarter stick of dynamite.