This story occurs somewhere in the midst of Sirius Trouble, during one, or possibly the other of the dastardly duo's trips to the South of France. It is a comic interlude and as such has very little point other than to amuse. If PWP didn't mean something incredibly different, we'd call it that – parody without a point. So perhaps we'll call it PWAP and confuse the hell out of everyone.
Sirius Black had been bored. When he was stuck in the house, going to gay Paris for a café had seemed like a good idea. It didn't any more. This was probably due to the fact that he was now on the run from Les Aurors. News in the Wizarding world doesn't travel fast, especially when the English ambassador to France would have in Malfoy's pocket, if his expensive bespoke robes had any. Which they didn't. Pockets would have ruined the clean lines and elegant simplicity of the fabric draped expansively, expensively and exactly over the family in question. Besides, what was the point in pockets when you have servants to carry things for you? And a big pimp stick?
Getting back to Black…
Sirius was getting desperate. He wasn't as fit as he used to be (well, that's debatable), his gym membership having expired sometime during the Azkaban period in his life, and he hadn't bothered to renew it. His personal trainer had warned him this would happen if he didn't work out. 'Hang on just a cotton picking minute,' he thought to himself, 'he bloody knew! He described this situation EXACTLY to me. Must have been a seer - bastard.'
Seeing no other alternative in sight, he shimmied up the nearest tree and tried to look inconspicuous. It didn't work.
"Come down from your tree Monsieur Noir"
"Um, no, I don't think I will, thanks all the same. I'm all warm and cosy up here."
'Ah, this must be the famous English sense of humour, yes?'
'No, that was just irony,' he shouted, still looking for an arboreal escape route. 'You'll know when we've got on to the famous English sense of humour when I start talking about breasts and farting you smug bastard!'
Sirius was notorious for talking rubbish to himself when he was stressed. We'd say that it was due to the trauma of Azkaban, but he'd always done it. What was a little unusual, and entirely due to his post-Azkaban jaunts around the world was that he now mumbled in the native language of the country he was in. Today was no exception.
'Ou est le cheval et le chevalier? Vraiment, c'est mon cheval prefere!'
He was rather surprised to see a knight in shining armour on a white charger galloping towards him. Not, as it turned out, as surprised as L'Auror at the foot of his tree, who had fainted.
The knight halted under the tree, taking care not to step on the French law enforcement officer any more than was absolutely necessary and lifted his visor.
'Next time,' growled the Potions Master, for it was he, 'you feel like a spot of wandless magic, I'd appreciate it if you didn't involve me AT ALL, let alone drag me half way across the country, sit me on a horse and dress me head to hoe in steel!'
Sirius laughed so hard he fell out of his tree.
The famous English humour bit is in fact half inched almost directly from Mr Pratchett, more specifically The Fifth Elephant. If you want to get really accurate it's page 236-7 of the 1999 hardback copy. Obviously, it's Discworld, so it is actually the famous Ankh-Morpork S.O.H…