Green’s Dictionary of Slang

push in the truck n.

sexual intercourse.

1938		J. Curtis They Drive by Night 212: I ain’t had a push in the truck since I come out of the nick and I’d like to have another before they top me.
1960		J. Franklyn Dict. Rhy. Sl.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.