Look, by the time you publish a story where a character says "That's super lit, homedog fam," all those phrases will become so overplayed and antiquated that the only people using them still are hipsters using them as the butt end of a joke or out-of-touch adults trying to connect with the hip young crowd.

My opinion? Capture the voice of the teen: the irreverent, half-ironic and half-sincere tone. The specific lingo is just dressing on top. Awesome is a pretty universal world, so you're safe there. But you wouldn't use "groovy" would you?