Green’s Dictionary of Slang

you know what n.

1. the vagina.

[UK] ‘Why do you Trifle?’ in Farmer Merry Songs and Ballads (1897) V 8: I’m sure I have as good a – You know what [...] Come let us do then, you know what.
[UK]R. Brathwait Barnabees Journal III Q6: To the Hole of Sara came I, / Once a bona-roba, trust me, Though now buttock-shrunke and rustie; [...] Her I caught by you know what-a.
[UK] ‘O Watt where art tho’ in Furnivall & Hales Bishop Percy’s Folio Manuscript of Loose and Humorous Songs (1868) 123: Cynthias you know whatt.
[UK] ‘Virgin’s Complaint’ in Pepys Ballads (1987) V 178: I have something, you know what, Yet no Man comes to wooe me.
[UK]D. Gunston (ed.) Jemmy Twitcher’s Jests 94: I kindly felt her — you know what.
[UK]‘John Long and His — I Know What’ in Funny Songster in Spedding & Watt (eds) Bawdy Songbooks (2011) III 36: John Long Miss Wiggins lov’d, and he / Up very early got, / To go to Kensington and she, / And taste her — I know what.
[US](con. 1910s) in Randolph & Legman Ozark Folksongs and Folklore (1992) II 725: Polka-dot hose and Spanish shawl, / And her little you-know-what paid for it all.
[US]H. Rawson Dict. of Invective (1991) 109: Carvel’s ring also became a euphemism for you-know-what.

2. the penis.

[UK]Urquhart (trans.) Gargantua and Pantagruel (1927) I Bk I 44: [They] would pass their time, in taking you know what between their fingers and dandling it, till it did revive and creep up to the stiffness of a suppository.
[UK] ‘Dick the Plowman’ Pepys Ballads (1987) III 170: Richard, give me that, I need not name it, you know what.
[UK]N. Ward ‘Gossip’s Visit’ in Miscellaneous Works IV 28: [She will] lye with any Man to ease her, That has but you know what to please her.
[UK]song title in Funny Songster in Spedding & Watt (eds) Bawdy Songbooks (2011) III 35: John Long and His — I Know What.
[US]Kryptadia II in G. Legman (1968) 344: His you-know-what was you-know-where; / If that wasn’t fucking, then I wasn’t there.
[US]A. Heckerling Clueless [film script] dionne: Puny. I like ’em big. cher: Ooh, I hate muscles. tai: You know I don’t really care either way. Oh, just as long as his you-know-what isn’t that crooked. I really hate that.

3. sexual intercourse.

[UK] ‘Why do you Trifle?’ in Farmer Merry Songs and Ballads (1897) V 8: I’m sure I have as good a – You know what [...] Come let us do then, you know what.
[[UK]J. Wade Vinegar and Mustard B: Thou shouldst well know, that I was never such a jade as to tire as thou didst, thou common Hackney thou? for when thou and a fellow was a doing I know what thou didst cry, Dig on, dig on].
[[UK] ‘Ballad’ Harleian Mss. 6913.61: That trounc’d em & bounc’d ’em till they were wonderous hott Then took ’em aside to doe I know not what].
[UK] ‘Cuckoo of the Times’ in Ebsworth The Roxburghe Ballads (1884) II 52: Under a hedge doing you know what.
[UK]Crim.-Con. Gaz. 6 Oct. 50/3: Says Sir John to his lady as together they sat, / ‘My dear, shall we sup first, or do you know what?’.
[US]E. De Roo Go, Man, Go! 35: I like to do other things better. Stay here and — you-know-what.
[US]J. Thompson Pop. 1280 in Four Novels (1983) 379: This fella, he probably says to the pig, ‘How about a little you-know-what, Piggie?’.
[US]S. King Dolores Claiborne 103: My Dad is trying to do you-know-what to me.
[UK]A. Sillitoe Birthday 39: Maybe she had a boyfriend, a bit of you know what going on with a neighbour or the window-cleaner.

4. (also what you know, you know) anything the speaker does not wish to name specifically; often used euph.

[[UK]W. Bullein Bk of Simples Fol. 27: Here is an herbe whiche light fellowes, merily will call Gallowgrasse, Neckeweede, or the Tristrams knot, or Saynt Andres lace, or a bastarde brothers badge, with a difference on the left side etc., you know my meaning].
[UK]W. Davenant Play-House to be Let Act V: With blood of Roman your Eunuch does grow fat; Such knaves wax cruel, having lost — you know what.
Behn Feign’d Curtizans 8: As I hope to breathe, your Face shines through your pouder’d Hairs, like you know what on a Barn-door in a frosty morning.
[UK] ‘In Praise of Chocolate’ in Ebsworth Merry Drollery Compleat (1875) 51: ’Twill make old women young and fresh, / Create new motions of the flesh, / And cause them to long for you know what, / If they but taste of Chocolate.
[UK] ‘The Phlegm Pot’ No. 32 Papers of Francis Place (1819) n.p.: There’s many a fine and flashy beau, that’s taking pills for what you know.
[UK] ‘The Dildoe!’ in Bang-Up Songster 17: They itch’d – and long’d – a deal, I wot, / For a little bit of you know what!
[Aus]Bell’s Life in Sydney 31 Dec. 3/2: Did you tell her you were as good as a costermonger’s — you know what, Mrs Johnson?
[US]F. Packard Adventures of Jimmie Dale (1918) I iii: Quite a little run out to my place, you know — and with, you know what, I don’t care to be out too late.
[US]T. Wolfe Look Homeward, Angel (1930) 153: ‘There are two things I want to see,’ said Mary, ‘a rooster’s you-know-what and a hen’s what-is-it.’.
[US]J. Weidman I Can Get It For You Wholesale 222: Boy, oh boy! Pick me that little redhead with the you know whats.
[US]J.H. Burns Lucifer with a Book 109: Got any you-know-what yet? Buddy Brown said to the kid. – No, sir, the kid said blushing.
[UK]C. MacInnes City of Spades (1964) 37: [of condoms] I want a taxi fare [...] and money to buy some you-know-whats.
[UK]C. MacInnes Absolute Beginners 58: I know in this country we treat the coloureds all like you-know-what.
[US]F. Kohner Gidget Goes Hawaiian 22: I don’t give a you-know-what.
[UK]A. Wesker Chips with Everything I ii: I got wise to the old man’s lies / And kicked him up his you know, you know, you know, you know what I mean.
[UK]P. Fordham Inside the Und. 174: The girl being [...] you-know-what about that time.
[US]Cab Calloway Of Minnie the Moocher and Me 168: I’ll slap the you-know-what out of you.
[US]A. Maupin Tales of the City (1984) 22: Just because I have some bizarre notion that my . . . you know . . . smells bad.
[US]R. Campbell In La-La Land We Trust (1999) 8: I’d like to see the bastards that mess with children strung up by the you-know-what.
[US]C. Hiaasen Stormy Weather 186: One of the brothers flashes a gun and tells me to you-know-what.
[US]Ian Dury ‘Mash It Up Harry’ [lyrics] And he wants a bit of Wembley up his you-know-what.
[US]F.X. Toole Pound for Pound 154: I don’t mean to be a pain in your you-know.
[US]S. King Finders Keepers (2016) 245: Ain’t that a crock of you-know-what.

5. the buttocks.

[US]C. Hiaasen Skinny Dip 190: You promised to see a surgeon [...] About the bullet in your you-know-what.