Underage Pressure

So I have a sister who is younger. She's 17 and at that age where hanging out with friends is life. Hanging out with these friends often means drinking and drugs. The drug part isn't the part i'm writing about, thank god. It's the drinking. Being older and of course over the legal age of drinking, she turns to me to be her outlet for drinks. This puts me in a small bind. Of course I was her age once and yes I admit I drank. But I never asked anyone to get me anything. I would be a hypocite to tell her not to drink since that's what I did when I was her age, but my morals get in the way. I hate knowing that I supplied minors with alcohol and if they happen to get in trouble that could one day come back to me. Of course she's going to be mad. But I'm upset with the position she's putting me in by even asking. So until we talk face to face, I will continue to ignore her phone calls and text messages and pretend i'm either asleep, not home, or phone is on silent, or even all three.