Green’s Dictionary of Slang

the vagina; thus attrib.

1952		J. Jones From Here to Eternity (1998) 153: I’m hot as Big Virginia’s double shunt. [Ibid.] 172: You better lay off, he told himself, this is no time to be inspecting shunt pictures.
2021		J. Ellroy Widespread Panic 307: He ells shunt shots to an undercover cop and gets five to eight.