It's actually a 1915 song written by George Henry Powell and Felix Powell, sung by soldiers in the trenches of World War 1 to boost their morale.
Pack up your troubles in your old kit-bag, And smile, smile, smile, While you've a lucifer to light your fag, Smile, boys, that's the style. What's the use of worrying? It never was worth while, so Pack up your troubles in your old kit-bag, And smile, smile, smile.
A kit bag is naturally a bag soldiers use to carry their equipment. A fag is British slang for a cigarette, and a Lucifer was a brand of match. – The preceding unsigned comment was added by 18.104.22.168 (talk).
- In the context it's a campfire song because it was stated as such in the movie - it was also later (after the war) sung as a campfire song though your statement does add some more history to the song. — Morder 23:09, 12 October 2008 (UTC)