Jack Mullen wrote
"And when the driver think he safely on the other side
He shouts back down the line to the man and he says
I fooled you, I fooled you
I got pig iron, I got pig iron
I got all pig iron
You just can't mention stock cars and pig iron without invoking Lonnie Donegan."
Or Huddie Ledbetter ('Leadbelly') who originated those lyrics in the the song, "Rock Island Line".