Green’s Dictionary of Slang

charity n.

[1920s+] (Aus.) a promiscuous woman or gay man, who ‘gives it away for free’.

In compounds

charity ass (n.) [ass n. (3)]

[1920s–50s] a woman who ‘gives it away’; thus sexual intercourse for which no payment is expected.

charity cunt (n.) [cunt n. (2)]

[1910s; 2000s] (US) a promiscuous woman who ‘gives it away for free’.

charity dame (n.) [dame n.]

[1940s+] (Aus.) a promiscuous woman who ‘gives it away for free’.

charity girl (n.)

[1910s+] (US) a promiscuous woman who ‘gives it away for free’.

charity goods (n.)

[1960s+] (US gay) a promiscuous woman or a male prostitute who gives sex but does not get paid.

charity moll (n.) [moll n. (1)]

[1940s+] (Aus.) an amateur prostitute, or a professional who undercuts her peers.

charity stuff (n.)

[1950s+] usu. of a male or female prostitute, sex for which one does not get paid; occas. the person themselves.

charity worker (n.)

[1940s+] (US) a promiscuous woman who ‘gives it away for free’.

SE in slang uses

In compounds

charity bob (n.)

[late 19C–1900s] a form of quick curtsy peculiar to charity-school girls.

charity case (n.)

[1960s+] an older sexual partner whose needs are gratified by a young man or woman out of kindness rather than desire.

charity fuck (n.) (also pity fuck) [fuck n. (1a)]

1. [1970s+] an act of sexual intercourse engaged in out of pity.

2. fig. use of sense 1.