From Charmion, actually.

And Eaton is the name of Canada's second-oldest department store chain -- the one that went so spectacularly bankrupt recently and was revived as a zombie of itself some months later.

>Vulgarity alert on<

"Screw Guns" is indeed sung to the "Eton Boating Song" tune in the Royal Regiment of Canadian Artillery, where it can also be obscenely parodized -- for example:

Sitting on top of a mountain
Playing with my diddle-doo,
Jerking off into my trousers
'Cause I've got fuck-all else to do;
Life as a Herbie* is thrilling
Whether at peace or at war,
And if God and the BC* are willing
I'll find out what my penis is for.

'Cause we're all fucking screwed up
Screwed up as we can be;
Life in the fucking Artillery
Is not what it's cracked up to be.
So if you're in need of employment,
And the money and pension's for you,
Stay out of the fucking Artillery,
Or you'll wear out your poor diddle-doo.

This particular parody was composed in the fall of 1975 by Bombardier Colin Niles Bailey and Gunner David Bulloch of the 3rd Regiment, Royal Canadian Horse Artillery, while enduring an exercise at Dundern, Saskatchewan, an army training area of stunning bleakness.