I've been seeing really good fanfics with these types of rules and stuff, so I thought maybe I could try it out for a bit! Also updates may take a bit, but I'll do my best!
1. Don't tell Sealand he's not a nation. Ever.
When Britain told him this, not only did Sealand curse in Scottish (due to Scotland teaching him the language) he brought out his wand because he's his little brother with magic powers and turned Britain into one of his scones. Afterwards Britain was found by America who threw it away and Britain transformed back whilst in the trash can.
2. Don't tell France Britain is secretly in love with him and wants to marry him.
France thought Sealand was joking (he secretly wasn't impressed with what happened yet) and when he explained it, France took the liberty of inviting Britain for drinks. Then they decided to go Britain's house and made so much sexual moans and groans and screams…while Sealand, Scotland, Ireland and Wales heard during the night. Oh, and London, the only girl.
"God, why didn't I become independent?" cried Scotland as he covered his ears with two pillows to mute the sounds.
3. Don't tell Japan FrUK is now canon
It wasn't Sealand who told Japan—it was Scotland by pure mistake when he confided to him about France and Britain having s** in their house. Not only did Japan spend two weeks nearby Britain's house stalking them, but he captured a lot of juicy moments and sent them to Hungary.
4. Don't tell Hungary FrUK is now canon
Hungary bolted out of bed after receiving the pictures from Japan, she joined Japan in the nightly stalking and made fanfiction (under an obvious username which I'm not allowed to speak for she'll kill me) about their steamy relationship.
5. Don't attempt to tie Britain in bed—naked—and have a secret camera in their bedroom (shaped as a monk)
Hungary and Japan did this—they got so much in bargain that they kept the video in their…private collection.
6. Don't tell France and Britain about the video above # 5.
France and Britain chased Hungary and Japan away and broke up later after that. FrUK was declared in every internet site dissolution (sadder than Prussia's, by the way)
7. Don't show Britain the photos of his relationship with France.
After having to delete the video, Japan and Hungary kept the photos in secret. They made sure not to break the rule in fear of losing their precious items.
8. Don't steal all of Japan and Hungary's collections…
Hungary and Japan went full our Attack on Titian on their asses and nearly made it an issue for the conference…
"WE MUST PUNISH THE MONSTERS FOR THEIR CRIME!" screamed Hungary furiously as she banged on the table with her frying pan. It was better than Prussia.
"THEY SHALL DIE IN HELL, DESU YO~!" screeched Japan angrily, people swore foam was forming in his mouth.
And guess who did it? Britain and France. They found their stash and decided to burn them. Big mistake.
9. Don't even think about giving Canada all those collections…just don't.
Canada thought 'yaoi' was some kid stuff. So he asked Japan and Hungary if he could have some. They gladly gave it to him. One day later, Canada returned them with a scarred face. The world was never the same after that.
10. AND FOR THE LOVE OF EVERYTHING HETALIA AND HIMA PAPA AND CHIBITALIA: DO. NOT. MAKE. PRESENTATION. OF YAOI. IN. CONFERENCE!
"And so, with the information we have gathered for our presentation," Hungary said sophisticatedly, "we believe that that ALL NATIONS WHO ARE MALES MUST BE TOGETHER! That is all."
Only Japan clapped for the wonderful presentation. Hungary and Japan were banned from ever presenting anything again.