Green’s Dictionary of Slang

1. (US) a novice, a recent initiate, e.g. a new whore.

1968		J. Colebrook Cross of Lassitude 339: She’s a new turn-out. She only got six months. She and Frankie should hit the streets about the same time.
1972		Milner & Milner Black Players 40: The process of taking a square broad (one who is not a prostitute) and teaching her game is called turning her out. This term is also used as a noun, as in ‘she was my second turn-out.’ Apparently the expression derives from turning someone out into the street or the bricks.
1979		‘Iceberg Slim’ Airtight Willie and Me 76: I had put too much trust in my power over a turn-out [...] the compulsive desire of any turn-out to flee the master who had put her new slick image together.

2. (US prison) a young prisoner who is forced into life as homosexual.

1965		implied in jailhouse turnout under jailhouse adj.
1972		B. Rodgers Queens’ Vernacular 201: turnout one who comes out of an all-male institution gay.