Random House Dictionary of American Slang
vol II. 1997 pg. 119
This very nice collection of collequializms (sic) gives reference to the song you cite:
3.l the vulva or vagina. - usu. considered vulger.
1938 J. colcord Song of Sailorman 99 "The Hog-Eye Man" Terry hints at hidden obsecenity in the name itself; but if this were case, the origniators have taken their knowledge with them. 1942 s.P. Bayard Hill country 75: [In] Greene County [Pa]... "Hog Eye" has an indecent meaning....."All she had to give me was a hog-eye and a 'tatler."...."I stepped right up and kissed her swett/And asked her for some hog-eye meat." 1920-54 in Randolph & Legman Blow Candle Out 788: The famele sex organ...cunt,...hog-eye...snatch [etc.] 1966 Longstreet & Godoff Wm. Kite The famle pudendum, called jelly-roll and hog-eye by Billy Brunswick.