Green’s Dictionary of Slang

Y n.

[abbr.]

1. (orig. US) the Young Men’s Christian Association (YMCA), often as the Y.

Topeka Dly Capital (KS) 17 Dec. 4/3: We Have a Tramp ‘Shack’ [...] An Organized Den of Tramps [...] outside the city limits. This rendezvous is situated about half a mile above the ‘Y’ on the Rock Island road.
[[US]N.Y. Tribune 23 Aug. 16/2: The ‘Ys’ of New Jersey [...] Her badge denotes that she is a member of the Young Women’s Branch of the Women’s Christian Temperance Union].
[US]Eve. Statesman (Walla Walla, WA) 18 Nov. 6/2: What the ‘Y’ is Doing [...] 2098 young women have been [...] taken to good families, or given rooms at the Y.W.C.A.
[US]R. Bolwell ‘College Sl. Words And Phrases’ in DN IV:iii 236: Y. Abbreviation for the college Y.M.C.A.
[US]G. Bowerman diary 15 Sept. in Carnes Compensations of War (1983) 19: Went to a very good concert at the ‘Y.’.
[US]S. Lewis Babbitt (1974) 167: Like all the fellows do at the Y.
[US](con. 1920s) Dos Passos Big Money in USA (1966) 800: I’m stayin’ at that kind of glorified Y over on Thirty-eighth Street.
[US]N. Algren Man with the Golden Arm 180: I’d do better to go to the Y. ’n take my belly off.
[US]Kerouac On the Road (The Orig. Scroll) (2007) 120: I went to the Y to get a room.
[US]J. Rechy City of Night 30: In the morning of the day I was supposed to meet him again, I moved out of the Y.
[US]G.V. Higgins Digger’s Game (1981) 22: The first thing I do, every morning [...] over to the Y.
[US]S. Morgan Homeboy 282: Skip the shower [...] beat Cicero out of the Y.
[US]E. White My Lives 110: No gay YMCAs except a fabled orgy palace of a Y in Milwaukee.

2. attrib. use of sense 1.

[US]Dos Passos Three Soldiers 25: The ‘Y’ man twisted his lean face into a facetious expression.
[US]H.A. Smith Life in a Putty Knife Factory (1948) 179: One afternoon I was on my way to the ‘Y’ pool.
[US]S. King It (1987) 301: My Gawd, someone put the Y-pool down in the Barrens, bellybutton lint and all!

3. the vagina; in phrs. dine at the Y under dine v.; eat at the Y under eat v.; lunch at the lazy Y v. [punning on sense 1 + the shape of a woman with her legs spread].

[US]R.A. Wilson Playboy’s Book of Forbidden Words 48: He goes down for a box lunch means he performs cunnilingus. New York wits sometimes elaborate this into he goes down to the ‘Y’ for a box lunch.

4. in pl., Y-fronts.

[UK]T. Black Artefacts of the Dead [ebook] I want to see everything, including his preference for Ys or budgie-smugglers.

5. the shoulders and arms as a place from where punches are thrown; in phrs. below [? the shape of the torso with arms raised].

In phrases