gangbusters

noun Informal.

1. a law-enforcement officer who specializes in breaking up organized crime, often by forceful or sensational means.
2. someone or something having great impact, usually in a positive way.
3. gangbusters, an outstandingly successful state or situation: We aren’t looking for gangbusters, but we’d like you to pass all your subjects this semester.

adjective Often gangbusters.

4. of or like a law-enforcement officer who uses rough, aggressive, or sensational tactics in fighting crime: The undercover agents avoided the gangbusters approach.
5. strikingly effective or successful: a gangbusters year for compact cars.
6. enthusiastic: I’m not gangbusters over the idea.

Idioms

7. go gangbusters, to be extremely successful: The movie went gangbusters.
8. like gangbusters, with great speed, intensity, vigor, impact, or success: The software market was growing like gangbusters. The hockey team came on at the beginning of the season like gangbusters.

n.

to come on like gangbusters (c.1940) is from U.S. radio crimefighting drama “Gangbusters” (1937-57) which opened with a cacophony of sirens, screams, shots, and jarring music.