Green’s Dictionary of Slang

1. (US) to extort.

1912

D. Runyon ‘The Fight Fan’ 15 Feb. [synd. col.] They pronged me a coupla checkers to set in a ringside seat .

2. to have sexual intercourse.

c.1940		in E. Cray Erotic Muse (1992) 211: He claimed he could prong more cunts with his dong / Than Ivan Skavinsky Skavar.
1942		in G. Legman Limerick (1953) 55: She went down on the gents, / And pronged the girls’ vents / With a clitoris reaching six inches.
1974		(con. 1940s) E. Thompson Tattoo (1977) 116: Who the hell could have told Brother Dub he had pronged his mother?
1979		D. Maitland Breaking Out 144: Compromising cows, pronging pigs and other gross offences of a bestial nature.
1985		J. Clanchy Lie of Land 229: Dear Gloria, I’ve wronged yer / shouldn’t have pronged yer.
2019		D. Winslow Border [ebook] Eddie finally gets tired of it, flips her over and [...] prongs her.

3. (US black) to enjoy oneself [poss. euph. for sense 1].

1947

M.H. Boulware Jive and Sl.

4. (US gay) to have anal intercourse.

1994

G. Indiana Rent Boy 72: I’m pronging him with my torso arched back.