Here's how I learned it at a boys' grammar school in Sheffield UK, circa 1960:

The dogs they held a meeting, they came from near and far
Some they came by railway and some they came by car
And as they all assembled according to the book
Each dog took off his arsehole and hung it on a hook.

Now as the meeting started, complete with ladies' choir
Some bloody bastard bulldog stood up and shouted 'fire',
The dogs they fled in panic towards the nearest hook
But to see if it was their own arsehole they didn't bother to look.

Now as you can imagine, the arseholes did not fit
Which made it rather difficult whenever they wanted to shit
And that 's the only reason a dog will leave its bone
To sniff another dog's arsehole to see if it's his own.

(to tune of 'Church's one foundation')

Oh, the benefits of a grammar school education......

Steve