Green’s Dictionary of Slang

jam n.3

[jam tart n. (2)]

1. an attractive woman.

‘Just the Identical Man’ [broadside ballad] And he made this young girl feel queer When he called me his jam, His pet and his lamb [F&H].
[UK]J. Ware Passing Eng. of the Victorian Era 159/1: Jam (Lower Class, 1880 on). Pretty girl – presumably of easy habits. The story of this word is very interesting. A girl of notoriety in Piccadilly was named ‘Tart’. She, in compliment to her sweetness, came to be styled jam tart, and the knowing ones would ask ‘Would you like a bit of jam tart?’ Then the tyranny of brevity asserting itself, the phrase became ‘jam’, which lasted twenty years.
[UK]E. Pugh Cockney At Home 62: But I felt somehow a bit sorry for young Soph. She was sech jam all over. And Billy, he was only kitchen stuff.
[US]A.J. Pollock Und. Speaks n.p.: Jam, a sweetheart (prison).
[US]‘Hal Ellson’ Duke viii: Jam – a girl of easy virtue.
[US]E. Folb Runnin’ Down Some Lines 243: jam n. [...] 2. Attractive female.

2. sexual activity, incl. intercourse, with a woman.

[UK]Barrère & Leland Dict. of Sl., Jargon and Cant.
[UK][perf. Vesta Tilley] The Parrot and the Parson [lyrics] She kissed him once or twice, said the Parson, ‘This is nice.’ / And the parrot shouted ‘Jam, jam, jam’.
[US]‘Hal Ellson’ Duke 54: I don’t pay for that other stuff. When I want jam I get it for nothing.
[US]W. Brown Run, Chico, Run (1959) 18: Why not let the kid come? I bet he ain’t never had no jam. Pitcher’ll toss him plenty.
[US]E. Folb Runnin’ Down Some Lines 150: Expressions like ‘I’m gonna get me some [...] jam, sweet potato’ reflect a sense of sweet-tasting sex, of nourishment, of being fed.

3. (later use US black) the vagina.

[UK]Randiana 10: I Ascertain the Meaning of ‘Real Jam’.
[UK]Farmer & Henley Sl. and Its Analogues.
[US]E. Folb Runnin’ Down Some Lines 243: jam n. 1. Female’s genitalia.
[UK]J. Morton Lowspeak.

In phrases

bit of jam (n.)

1. the vagina; thus have a bit of jam, to have sexual intercourse.

[UK]Farmer & Henley Sl. and Its Analogues.

2. an attractive woman.

[Aus]Bulletin (Sydney) 5 Mar. 8/2: A most affecting incident occurred at the theatre on Monday evening last, when that ‘sweet little bit of jam,’ Miss Adelle, stepped on the stage.
[Aus]Bulletin (Sydney) 26 Sept. 9/3: [S]ome of his young ladies are ‘bits of jam.’ In thus describing their charms we are quoting from the Variety Entertainment. They were, furthermore, referred to as ‘tarts,’ but we won’t go so far as to call them ‘tarts.’ We will merely smack our little lips and apostrophise them as ‘sweets.’.
[Aus]Dead Bird (Sydney) 22 Nov. 5/2: Leander Rooster, though an estimable man, / Is quite susceptible to small tit-bits of jam, / And Hero, so charming, innocent, and sweet, / The Rooster thought her good enough to eat.
[UK] press cutting in J. Ware Passing Eng. of the Victorian Era 30/2: He kisses me, he hugs me, and calls me his bit o’ jam, and then chucks me down stairs just to show me there’s no ill feeling; yet I love him like anything.
lawful jam (n.)

one’s wife.

[UK]W.E. Henley ‘Villon’s Good-Night’ in Farmer Musa Pedestris (1896) 174: Gay grass-widows and lawful-jam – / A mot’s good-night to one and all!