If you imagine that you are flying, does that mean you are actually flying?

Of course. You can just say things now and that makes them true, if they fit the dominant narrative. If you disagree with what the party says you obviously hate your country.

Try doing that for 6,000 years and see what happens

It's commonly known as .... religion ... but if it only appears and occurs for short periods, it's known as a cult

when I read party, I was thinking of DnD, so I thought "if the rule of cool applies, then yes"

Recently got into rpgmemes and started wondering how high the party would have to roll to persuade someone into believing two plus two equals five.

All language is a mental model, shared between the speaker and the audience. Math without any context like this is just a language like any other, encoded for two or more parties to communicate something abstract.

If the speaker and the audience both believe two plus two equals five, then it is true.

"Five" might look like "4" and be called "Five" or perhaps "Two" is instead written "2.5", but the truth of the original statement is only actually dependent on the shared mental model of the speaker/audience.

There is no telling what the objective meaning could be, if there was ever an objective meaning at all. For example, the entire meme itself could be a password that means "buy Bitcoin".

Or for another example, two plus two is five if this is a shorthand for two 1.25lb baskets of strawberries plus two 1.25lb baskets of strawberries being equal to five 1lb baskets of strawberries.

You might say "Hey! That's adding outside context! Not fair, it's nonsense!" but consider that the original statement didn't specify any context for the numbers at all. What are the numbers in reality, without any context? They represent nothing but the concepts they represent until they relate to a physical context anyway, just like any other fragment of communication.

My head went straight to D&D and was curious what shenanigans the party was trying to accomplish with his.

For many on Lemmy, yes.

Truth doesn't matter anymore.