I frequent a couple of writing boards, and consistently hear a question like:
Do teenagers still say, "That's RAD!"? or whatever. It can be anything from slang, to ways of classifying relationships, to just general terms of excitement. (Note: Teenagers do not say That's the Bee's Knees, Homey! I'm just saying.) Each time I read one of these posts, I'm not sure how to respond.
First, I'm a youth pastor by day (fabulous ninja by night... and writer.) So I'm around teenagers every day of the week. I hear everything they say (unfortunately) and most of the time, they don't use particular slang. I feel like I can enter into these discussions on the boards and give some fairly accurate information - even more so than parents, because I see and meet these kids in an entirely different place.
However, part of me wants to scream every time I see something like this. Why? Because it. doesn't. matter.
No. Really. It doesn't matter if a kid says they're going out or dating. Because I think everybody knows what it means. It especially doesn't matter if you're trying to tap into what's cool right now, because by the time your book comes out it's going to be completely irrelevant.
I don't want to sound like some crotchety old man here, but I think it's important. As the author, you're supposed to create a 'culture' for your book. What do teenagers say in your world? Even if it's contemporary, you still have free reign to decide the speech patterns in your story. And, in my opinion, this makes for a better and more nuanced narrative. I look at M.T. Anderson's FEED as an example of a writer/book that does this perfectly.
Not doing this, I believe, sterilizes your writing. It strips everything out of your voice as you're trying to latch on to the cool words, or the most current phrases. Of course, you shouldn't have some teenager speaking in Old English all, Thou hast forsaken me, thou shalt be smited!
But, then again, how funny would it be to have a contemporary teen who decides to speak only in Old English?