in-and-out boy, n. — Green’s Dictionary of Slang

in-and-out boy n.

1. a second-rate criminal, i.e. one whose life alternates between being in and out of prison.

1929		C.G. Gordon Crooks of the Und. 70: Poor boobs. No wonder they are termed ‘in-and-out boys!’.
1937		J. Curtis You’re in the Racket, Too 191: ‘Soon as I come out of that lot I gets lifted again for dragging a parcel out of the back of a delivery wagon.’ ‘Regular in-and-out boy, ain’t you?’.
1959		C. MacInnes Absolute Beginners 78: I could introduce you to several [...] in-and-out boys and several corpses.

2. (UK Und., also in-and-out man) an opportunist thief [one who goes quickly in and out of the house he is robbing].

1984

Partridge DSUE (8th edn) 595/1: since ca. 1945.