Green’s Dictionary of Slang

jocker n.1

[jock v.1 ]

1. [late 19C+] (US) a tramp who travels with a younger partner, working for him and poss. acting as his catamite.

2. [20C+] (US, also jocky) a male homosexual, the ‘husband’ of the couple.

3. [1910s+] (US, also jock, joko) a predatory homosexual, esp. in the context of prison, who forces his attentions on younger/weaker men or boys.

4. [1960s–70s] (US) a lecher.