Green’s Dictionary of Slang

choirboy n.

1. [1930s+] (US Und.) a novice thief.

2. [1940s+] (US) an innocently honest person; a naive and foolish person.

3. [1960s] (S.Afr.) an accomplice, a young man who plays a supporting role in a crime.

4. [1970s] (US gay) a novice male streetwalker.

5. [1970s+] (US) a novice police officer.

6. [1990s+] (US black) a derog. term for a black person seen as embracing white values.

7. [2000s] (S.Afr. gay) a homosexual male; thus in the choir adj., homosexual.