POLITICO found the document outlining ground rules for the first official meeting between David Davis and Michel Barnier. | Getty Images Unreality check Leaked! Brexit talks protocol agreement Top secret document reveals the do’s and don’ts of exit negotiations.

Brexit talks get underway on Monday morning, the start of a two-year process that will doubtless feel like a decade. In preparation, the U.K. and EU have been holding "talks about talks" to prepare the ground for the first official meeting between David Davis and Michel Barnier and their teams of advisors and hangers-on.

At their meeting last Monday, Britain's Oliver 'Real Mr. Brexit' Robbins and the EU's Martin 'Monster' Selmayr hashed out the rules of protocol and wrote them out on goat parchment, an original of which POLITICO found in a trash bin behind the Berlaymont building. Its authenticity couldn't be independently verified.

Do's and don'ts of Brexit talks

For the EU side

Don't make fun of Theresa May. She's having a hard time and it's not her fault (no, wait, it is ... )

Don't compare British politics to Italian politics, circus shows, the Apocalypse, Trumpworld or anything in fact. Relatedly: Don't utter the phrases "keep calm and carry on" or "strong and stable" with a sarcastic grin — or better yet, never use them at all.

Don't keep banging on about that nice Monsieur Macron.

Don't speak in foreign languages. Michel Barnier, like many French people, speaks English but refuses to do so in the company of Brits.

Do pretend this is a negotiation of equals.

Do order lunch, you're on home turf.

Don't go overboard. Brussels' two-Michelin-starred Comme Chez Soi has potato mousseline with crab, shrimps and Royal Belgian caviar at €177 a head, which might be a bit much. David Davis will be happy with a cheese and pickle sandwich.

Do let Jean-Claude Juncker order the wine.

Do keep a tab on the expenses (all of the costs of the talks will be added to the Brits' divorce bill). Coffees, biscuits, pens, sheets of toilet paper ... put that on the list.

Don't let Guy Verhofstadt into the meeting room.

For the U.K. side

Don't make a face when you get served poor quality tea (without milk!).

Do compliment your hosts on the lovely new European Council building — with a straight face, please.

Do make jokes about how terrible things would be if Jeremy Corbyn were here.

Don't perpetuate the stereotype of the Brit abroad by speaking loudly and slowly in English, with extra pointing for emphasis.

Do try at least one word in French. Bonjour, perhaps. Not merde.

Don't cover everything with a thick layer of irony and/or sarcasm (and when it comes to lunch, ketchup).

Don't for goodness sake invite Boris.

And of course ... don't mention the war.