Green’s Dictionary of Slang

(US) the vagina.

1984		(con. WW2) T. Jones Heart of Oak [ebook] Now the fellers they came, and the fellers they went— / And the price went down to twenty cents— / From sweet sixteen to ninety-two— / She had to live on— her ringer-ranger-roo!
1984		Partridge DSUE (8th edn) 978/1: since ca. 1930.