Green’s Dictionary of Slang

(US) having sexual intercourse.

1928		in Randolph & Legman Ozark Folksongs and Folklore (1992) I 328: As printed in The Book of a Thousand Laughs, by ‘O.U. Schweinickle’ (Wheeling, West Virginia, 1928) [...] ‘Hickory is the hardest wood, / Jazzing does the ladies good, / It brightens their eyes / And widens their thighs, / And gives good exercise.’.
1933		J.T. Farrell Gas-House McGinty 215: The bird who invented jazzing was a bum inventor to throw in all the complications and grief.
1946		W.L. Gresham Nightmare Alley (1947) 66: As if jazzing wasn’t what they all want.
1958		Murtagh & Harris Cast the First Stone 205: ‘She asked if I wanted to do a little jazzing,’ he told the court.