Green’s Dictionary of Slang

back-door n.

[pun on SE]

1. [late 16C+] (also back avenue, back way) the anus.

2. attrib. use of sense 1.

3. [mid-19C] (also back premises) the vagina.

4. (US gay) homosexual anal intercourse.

In compounds

backdoor action (n.) [-action sfx]

1. [1940s+] sodomy.

2. see also SE compounds below.

backdoor action (n.)

[2010s] hetero- or homosexual anal intercourse.

backdoor kicker (n.)

[1990s+] a male homosexual.

back-door man (n.) (also back-door(s) gentleman, ...merchant, back-doors man) [merchant n.]

1. [18C–19C; 1950s+] one who practises anal intercourse, esp. a homosexual; in homosexual anal sex, the active partner.

2. see also SE compounds below.

backdoor work (n.)

[late 19C+] anal intercourse, sodomy.

In phrases

cop it up the back door (v.)

to submit onself to anal intercourse.

go up the back door (v.) (also go in the back door) [pun on SE]

[1930s+] to have heterosexual anal intercourse.

SE in slang uses

In derivatives

back-dooring (n.) [the adulterer lit. or fig. uses the back door rather than the front door]

[1980s] (US) adultery.

In compounds

backdoor action (n.) [the (lit. or fig.) use of the more private back door + -action sfx]

1. [1970s+] (US) adultery .

2. see also sl. compounds above.

back-door man (n.) (also back-door husband, ...merchant, back man) [the (lit. or fig.) use of the more private back door]

1. [1920s+] (orig. US black) an adulterer.

2. see also sl. compounds above.

back-door trot (n.) (also back-door trots) [SE back-door that leads to the privy + SE trot/trots n. (1)]

1. [19C+] diarrhoea.

2. [1950s+] over-frequent urination.

In phrases

work the back door (v.)

[1900s] (US) to act in a deceptive, corrupt manner.