Like insisting Italians arent white for example or that the Netherlands don't exist.
I think my favourites are those that take notice of the weird things certain national groups do online - Like "[X] WAS SERBIAN" and "[person] come to Brazil". I like how unhinged they are. Once you see a Serb insist Elvis was serbian then you kinda get it.
Hobby spaces have a lot of these kinds of jokes. WH40K people writing like tech priests or orks, discoposting here, that kinda stuff.
Salafiyya jihadists use the ☝️ instead of 👍 or ✌️ in a lot of their photo ops (probably used by others as well) to represent tawhid—the oneness and indivisibility of God.