This is me, a linguist, being pedantic but what you’re describing (a particular pattern of speech/grammar/vocabulary indicative of a defined group) is technically a dialect; an idiom is a turn of phrase that means something other/additional than the literal meaning of the words (“raining cats and dogs” or “see the light” etc etc). You may have been thinking of an idiolect, which is the particular dialect of a single individual.
And if I, a linguist (an intellectual 🧐), hear Tumblr English out in the wild, I get so excited. Genuinely, I seriously considered writing my masters thesis on tumblr english and only didn’t because my advisor was a bit of a stick in the mud. This is a VERY Exciting Time™️ for linguists because the advent of the internet (and more specifically areas of the internet that encourage communities to form among people scattered across the globe) has created an era of exceedingly rapid language change, and gives us a huge opportunity to study how language changes on a much shorter timeline than usual. Throughout human history, geography has been a huge limiting factor in language bleed, transmission, and change; but now we have the ability to talk to people from all over the globe regularly enough that we are picking up vocabulary, grammar, and linguistic markers from all over the world.
Like, do you get how fucking cool it is that english speakers who have never visited Asia are able to use borrowed words like isekai and honorifics like -san fluently?? Do you get how many idioms and weird little grammatical constructions we’ve created that are unique to OUR dialect of english? Think of pissing on the poor or (like I used earlier) me, an intellectual. Our dialect, here on this hellsite, is the only one I can think of that has created a significant catalogue of complex tone markers specifically for the written form to compensate for the shortcomings of the written word in communicating meta-linguistic information like sarcasm or mockery or excitement. This dialect, primarily created in the written form (which is nearly UNHEARD OF), exploded onto the linguistics scene in 10 or 20 years when normally it can take centuries for dialects to distinguish themselves. It's academically BONKERS and I am HERE FOR IT. It's in the same realm as Nüshu, the Chinese written script only used by women.
TLDR: As linguists we are collectively shitting our pants about this fucking dialect and are OVER THE MOON to hear it 'in the wild.'
