Green’s Dictionary of Slang

social worker n.

(US gay) a homosexual who finds partners among the homeless and destitute.

[US]Lavender Lex. n.p.: social worker:–A homosexual who cruises among the unemployed and destitute. Can be a slightly mocking term applied to those who assume a fatherly or motherly-role.
[US]B. Rodgers Queens’ Vernacular 186: social worker 1. homosexual who cruises the welfare lines.