Transcribed from the sheet music at The Lester S. Levy Collection of Sheet Music.
A 1918 recording by the American Quartet can be heard at The Virtual Gramophone.

KEEP YOUR HEAD DOWN, FRITZIE BOY
Lieutenant Gitz Rice
"Inspired by a Brave Tommy and written at the Battle of Ypres 1915."
Publication: New York: Leo Feist, Inc., 1917.

1. Over in the trenches, up to their eyes in clay,
Billy and Jack and Jimmie and Joe are singing all the day.
When they see a German sticking up his snout,
They give him a chance to get out of France when they all shout:

CHORUS: Keep your head down, Fritzie boy!
Keep your head down, Fritzie boy!
Late last night in the pale moonlight,
I saw you! I saw you!
You were fixing your barbed wire
When we opened rapid fire.
If you want to see your "Vater" in the "Vaterland,"
Keep your head down, Fritzie boy.

2. Soon the Boche got wiser, hearing this ev'ry night.
He sent us a bunch of rifle grenades to give us all a fright,
But he couldn't stop us; we let out a roar:
"We'll give you your fill of old Kaiser Bill and this d----* war!"

[*Printed as shown in the sheet music, but sung as "darned" in the recording.]