Green’s Dictionary of Slang

to have sexual intercourse.

1960		‘Sheldon Lord’ A Woman Must Love 51: [H]er mind was probably going to change again and again until she either broke off with him entirely or wound up rolling around in the hay with him.
1967		C. Cooper Jr Farm (1968) 151: ‘You look like you goin to roll in the hay,’ Joe Antman snickered.
1969		‘Iceberg Slim’ Pimp 28: The country girl had rolled in the hay with the city slicker.
1971		L. Sanders Pleasures of Helen 131: ‘What the hell’s the point of being married if you can’t jump in the hay any minute you feel like it?’.
1986		L. Heinemann Paco’s Story (1987) 64: Ah’d love to roll in da hay wit-cha, my sweetes’ little patootie.