lol .... its a massive thing with all teenagers 13 and up, you can't really stop it they just have to make the choices themselves. Id be more worried about pot than alchohol.
Why be more worried about pot? alcohol is far more dangerous(increased violence, road kill etc.) and can actually be very addictive. Say no to all drugs, including alcohol(although i have noticed that saying "no" to a bottle of bourbon doesnt stop you from getting drunk when you drink it).