Green’s Dictionary of Slang

third adj.

SE in slang uses

In compounds

third base (n.) [baseball imagery]

(US) contact with the vagina or penis, in the context of sexual exploration (cf. first base n. (1); second base under second adj.; home run n. (2)).

[US](con. 1944) N. Mailer Naked and Dead 551: I got to third base last night.
Little Blue Patakha on Urban Dict. [Internet] Third Base The last base before sex, entailing contact with the main sexual regions, a handjob or a blowjob (fellatio) for guys and fingering or giving head (cunnilingus) to the girl. ‘We got all the way to Third Base on my friend’s roof when I bent down to give him his first blowjob ever.’.
[US] posting at advicechick.com 8 Nov. [Internet] We had been just hitting third base (kiss/feel).
third beer (n.)

(N.Z.) a woman, generally, a girlfriend, who is considered plain and unexciting.

[NZ]McGill Reed Dict. of N.Z. Sl. 211: third beer A woman, usually a girlfriend, who is not attractive or very exciting; dull, ordinary.
third degree

see separate entries.

third leg (n.)

the penis.

[[UK]Harris’s List of Covent-Garden Ladies 69: [She] is so very careful of her health, that befopre she receives her guinea, she must examine every one of her partner’s legs].
[Aus]Satirist & Sporting Chron. (Sydney) 25 Feb. 2/1: The hon. Attorney General wished to give his half for any benevolent purpose — [...] from what we can gather, he is only anxious to give his third (q. leg) to such charitable purposes - of that anon.
[US]R.A. Wilson Playboy’s Book of Forbidden Words.
[US] P. Munro Sl. U.
[US]Randolph & Legman Ozark Folksongs and Folklore I 452: The penis [...] often frankly called in American children’s slang, the third leg or middle leg.
[UK]B. Dark Dirty Cockney Rhy. Sl. 82: Mystic Meg third leg.
[UK]Guardian Rev. 6 Aug. 13: He calls it his ‘third leg.’.
third rail

see separate entries.

third sexer (n.) [SE third sex, homosexuality, coined by sexologist Magnus Hirschfeld (1868–1935)]

(US) a homosexual.

[US]R.O. Scott Gay Sl. Dict. [Internet] third-sexers: [1930s New York] Homosexuals.
third-tierer (n.)

(US) a prostitute who cruised the third tiers of theatres.

Wag (N.Y.) 7 Dec. 2/3: One of the saints of Dr. S---’s Church, whoat [sic] used to be a third tierer in all the southern theatres.
third-world briefcase (n.) [SE third-world, i.e. non-white]

a large portable stereophonic tape deck/radio, particularly popular among black youths in the US and UK.

[Aus]R.G. Barrett You Wouldn’t Be Dead for Quids (1989) 87: And I’ll shove that fuckin’ Third World briefcase up there [i.e. ‘your arse'] as well.
[US]Eble Campus Sl. Fall.
Urban Dict. [Internet] wog box A large stereo carried held to the ear by some tinted folk. Also 3rd world briefcase. I saw one of those new wog boxes in Dixons that puts out about 100 watts.
[US]Eble Sl. and Sociability 15: Although slang items come and go, it is easier to pinpoint, and in some instances to explain, the comings than the goings. Ghetto blaster, jambox, and third world briefcase naturally did not come into this language before this past decade, because the ‘portable stereo tape deck’ had not been invented.

In phrases