Let me begin with congratulations on a social marketing campaign that will totally get people talking and thinking all over the country. GLSEN, the Ad Council and ArnoldNYC should be entirely proud of that. And their teachers' guide, downloadable free from http://thinkb4youspeak.com/, is awesome.
That said, I hope that teacher trainers all over the country will ask teachers NOT to take the ads literally and NOT to try their strategy at home ... insulting young people to get them to stop insulting others. It's like hitting kids to get them to stop hitting. While it may be funny in the context of an ad and when you aren't the youth in question, it's neither effective nor ethical in the real world. The ads are meant to get people talking, NOT to model good ways to intervene when people say, "That's so gay!" to mean something is stupid or boring.
I use a strategy a teacher once taught me. I use my own name, Beth, as an analogy and ask the offender how they think I would feel if I heard people call disgusting things "so Beth" 99 times a day. Using my name or my own identity is way preferable to using that of the student. Attacking a student, even in a sarcastic way, only reinforces the idea that meanness is funny. It doesn't build empathy.
Another strategy is so simple that my niece used it successfully when she was about 9 years old to shut down a harassing situation. Two girls were surveying their class on the playgound about which of two classmates they liked better. Sarah said, "That's so mean!" One of the offenders tried to blame the other and Sarah just repeated, "I don't care; it's still so mean." After about the 3rd time she called their survey mean, they gave it up altogether.
Anyway, I hope teachers -- and students for that matter -- will find some alternative to the "That's so Emma and Julia" of the ads. Maybe it sounds saccharine, but life is too short to run around hurting one another, especially in the name of prejudice reduction.