I am a HUGE fan of shanties and this is one of my favorites. My, what a lively discussion! My conclusion is, like so many bawdy songs of old, hog-eye has a double meaning and those who get it, get it, and those who don't can still enjoy the song and not feel like they're out of the loop.

Somewhere I read that a navvy was a railroad worker but as so many of you have said, it likely has other meanings. (I also really dig the Navvy Boots song.) --KC