Green’s Dictionary of Slang

1. to fight; thus swinging out n.

1962		(con. 1953–7) L. Yablonsky Violent Gang (1967) 27: Anybody who doesn’t swing out will have to tangle with me when we get back.
1972		T.M. Kochman ‘The Kinetic Element in Black Idiom’ in Kochman Rappin’ and Stylin’ Out 161: Some words and expressions referring to fighting embody purely kinetic elements, such as ‘swinging out’ and ‘jitter-hopping’.

2. (US campus) to lose emotional control.

1967–8

Baker et al. CUSS 208: Swing out Go wild.

3. to associate with.

1968

N. Heard Howard Street 215: To swing out with him showed she was still a ‘soul-sister’ and dug her own kind.

4. (US police) for an officer to begin their regularly scheduled days off.

1990		M. McAlary Crack War (1991) 73: I swung out for a couple of days. When I came back [etc.].
2005		R. Cea No Lights, No Sirens : Now, John Conroy had swung out, so we would get to the Shah [i.e. a possible informant] before John did.