Green’s Dictionary of Slang

1. (US) an incompetent, esp. in sport.

1899–1900

C.L. Cullen Tales of the Ex-Tanks 119: The Sergeant socked it to the cop for being a pinhead, a lightweight, and an in-and-outer.

2. (US Und.) a second-rate, petty criminal.

1959

J. Thompson Getaway in Four Novels (1983) 74: An underworld in-and-outer who had acquired a bad name for reliability.

3. (US Und.) a criminal who is arrested, but never actually charged and jailed.

1974

V.E. Smith Jones Men 123: I can’t find any evidence he ever spent a day in jail [...] One of those in-and-outers.