Green’s Dictionary of Slang

1. a gun.

2003

Music from the Corner ‘S.D.R.R.’ 🎵 We ain’t trying to be dead before the spengs come.

2. a form of strutting walk.

1995

Francis-Jackson Official Dancehall Dict. 49: Speng a type of strutting walk characterised by an intense slouching of the shoulder, accompanied by buttoning up of one’s collar.

3. an urban gangster.

1995

Francis-Jackson Official Dancehall Dict. 49: Speng [...] a toughie.

4. a slut.

1991

Shabba Ranks ‘Paak Yu Benz’ 🎵 A gyal shii go kip / Faiv man fren [...] Shii iz ongl a speng.

5. a fool.

1992		in R. Graef Living Dangerously 166: My solicitor, he’s a ‘speng’ (stupid) man.
1997		C. Newland Scholar 257: Yeah you’re right, I’m a speng.