Actually the opposite is more than likely true. If you're trying to sound "hip" (outdated choice of word) as you put it that would indicate actual concern for what other people think about how you talk.
I know that from growing up in Detroit I have a way of conversation that many would find distasteful. I can control it when I write but it's not the real me when I do. And I know several others from the north east that say "Idee'r" when they know darn well it's spelled "Idea".
I talk like I talk (old Detroit comes out especially during emotional times like when our country is intentionally being guided to hell) and this writer writes as he writes more than likely because neither of us give a rat's a - - what any douches may think of it.