I'll tell you what the cop who just came to toss out the underrage kids drinking in my hotel told the ones who were't causing the problems but were there nonetheless; you might want to find yourself some better friends; you're at an age where the company you keep matters now. Of course, not a direct quote, but that was the gist of it. They hardly even knew these kids but decided to participate in a party where half the people were not of age to be drinking and a couple almost got taken to jail. Now, you said that you aren't drinking, but I'm going with mscap's direction of advising you in case you choose to even be there.
Don't just think in terms of what's going to get you ahead and what's going to make a difference just because 'everyone else is doing it'. Be the best person and applicant you can be. Even stupid mistakes can make you look one notch less than someone else. Maybe everyone else has drank and drank underage and they'll be honest about it, and maybe there's one person who didn't. Many people have tried marijuana at least once, but you know what, there are those few people who never have, and they're one notch above everyone else who did.
We must all fear evil men. But there is another kind of evil which we must fear most, and that is the indifference of good men.
-Monsignor, Boondock Saints