Verse:
The war is raging
I'm on my boat
Ferrying CIA.
There's never been such a day
Here or on Cam Ranh Bay.
But it's December the 24th
We're fighting gooks from Vietnam north ...
Chorus:
I'm dreaming of a Cambodian Christmas
Although there'll be no snow or ice.
On a secret mission
With bullets whizzing
Ouch! My butt's shot full of rice.
I'm dreaming of a Cambodian Christmas
With every Charlie that I shoot.
Nixon's war is stealing my youth
Hope the girl I marry has some loot.
I'm dreaming of a Cambodian Christmas
Just like the one I never knew.
Wonder why my shipmates
Express such deep hate
For me, I really have no clue.
I'm dreaming of a Cambodian Christmas
I hope my gift's a Purple Heart.
War crimes in which I played a part
Will give my political career a start.
Well done, thanks. ;-)

Answer: It assumes the reader knows all about the Kerry/Cambodia kerfuffle. BUT, the story has not been mentioned in the Observer (or any other mainstream paper). Yet the cartoonist is comfortable that his readers will get it. This is a fine example of a story making its impact on the web despite the MSM's best attempts to stifle it.