American bomber crews in England during WWII sang as follows:

            Down in Ruhr Valley, valley so low,
            Some chairborne bastard, says we must go.

            Flak loves big bombers, fighters do too.
            P-51 boys, whe-ere are you?

            Write me a letter, send it to me,
            Send it in care of, Stalag Luft III.


"Stalag Luft III" was a German prison camp for captured Allied fliers.
Think "The Great Escape."