Green’s Dictionary of Slang

snapping turtle n.

(US) the vagina.

1958		Southern & Hoffenberg Candy (1970) 153: Then I hit him with my snapping-turtle just as he was getting his big soulful Hebe nuts off. [Ibid.] 154: I take pen in hand and say how very much I would like to have some of your snapping-turtle puss.
1970		T. Southern Blue Movie (1974) 171: You know what they call that back in Texas? [...] Snapping-turtle pussy.
[c.1973		J. Thompson ‘Sunrise at Midnight’ in Fireworks (1988) 184: That tiny Hairy-ette who rests so cosily between my thighs is the most wondrous of kitty-kats (though given to snapping in the fashion of turtles)].
1980		J. Sakol Hot 30 145: [...] breaking something under his nose that almost beheaded him and expertly guiding his distended eel into her snapping turtle.
[1988		(con. 1930s) C.E. Lincoln The Avenue, Clayton City (1996) 6: I had a girl once with a poontang like a snappin’ turtle].
2003		‘The Cooter Monologues’ at www.pinkhairedgirl.com 20 Jan. 🌐 Cooter. My friend Fran used to use this, and I find it really amusing. [...] I think that there’s some kind of a turtle that people call cooters, too. [...] It may be a snapping turtle/vagina dentata thing.
2011		D.R. Pollock Devil All the Time 73: Her only redeeming feature was the thing between her legs, which some had said reminded them of a snapping turtle.