The language convention that the author has used to separate the declarative sentence from the disruptive phrase in this excerpt from "Totally like whatever, you know" are the em dashes.
The disruptive phrase is something that doesn't quite belong there, and should be moved to other parts of the sentence so as not to disrupt the natural flow. Here, the disruptive element is set off from the rest of the sentence using em dashes: so--called because they used to, like, DECLARE things to be true, okay, as opposed to other things are, like, totally, you know, not.
