Here you are, Marion:

^^ THE MAN WITH THE TERRIBLE KNOB
(Enoch Kent)

Chorus:
I'm the man the well-paid man in charge of the terrible knob
The most pleasing thing about it it's almost a permanent job
When the atom war is over and the world is split in three
A consolation I've got or maybe it's not there'll be nobody left but me

I sit at my desk in Washington in charge of this great machine
More vicious than Adolf Hitler more deadly than strychnine
And in the evening after a tiring day just to give myself a laugh
I hit the button a playful belt and I listen for the blast

If Brezhnev starts his nonsense and makes a nasty smell
With a wink and a nod from Nixon I'll blast you all to hell
And as for that fellow Castro him with the sugar cane
He needn't hide behind his whiskers I'll get him just the same

If my wife denies me conjugular rights or my breakfast milk is sour
From eight to nine in the morning you're in for a nervous hour
The button being so terribly close, it's really a dreadful joke
A bump of me arse as I go past and you'll all go up in smoke

Now I'm thinking of joining the army - the army that bans the bomb
We'll take up a large collection and I'll donate my thumb
For without it I am helpless and that's the way to be
You don't have to kill the whole bloody lot to make the people free

This is the Dubliners version. The names rather date the song, of course - not much longer now and we'll have to explain who Nixon and Brezhnev were! Not Castro yet, though.
I've just watched Stanley Kubrick's 'Dr Strangelove' for the first time, and the song seems to me to be the musical equivalent of that film - funny, because it deals with an inconceivable event, but it does leave an uncomfortable feeling, and India, Pakistan and China have just reminded us that nobody so far has donated their thumbs, metaphorically speaking. (And even if they had, the third verse makes clear they'd need to donate much more than that to remove the threat to us all ...)
The tune was also used for an Australian bush ranger song, 'Dunn, Gilbert and Ben Hall'.