Replying to New Year's Eve trip

In other words this is S-trip. In my junior year at high school, and always have a trip to Quebec City every year. As the drinking age is already lowered its a huge party, very sick time. Not to mention some good skiing. Parents have heard stories and what not about what goes on. All my friends are going. Convincing is going not so great, told them its just to ski. Anyone ever go on this trip? I'm trying to think of some ideas to convince them or even just make a plan to go without them knowing. Any thing would be great.