To Party or Not to Party?

My sister is cool. Sis is nice, smart, funny and extremely artsy.
Somehow, I've managed to trick her into thinking that I am cool, as well. This could be attributed to the fact that although cool, she's a mere 15-years-old and has not wised up to the ways of the World.
I won't tell you what I did, because although no family member knows of this blog, somehow writing it will ensure that my mother will find out. As a twenty-eight year old married woman, I am still terrified of my mother’s wrath.
All I will say is that last fall I did something in front of Sis that surely will result in the demise of her future. It was not just me, though. The Mister and Aunt J were there to help me make sure my little sister will not make it in the World. –Hey, if I go down, I’m taking them with me; I’m taking all y’all with me. That’s just how I roll.
So, the thing is… do I never do this thing in front of her again (of course, I mean until after she’s eighteen), or do I continue to live my life normally while she’s around?
When she visits this summer (she’ll be 16 then), can I take her to parties at friend’s houses? I’d never let her get trashed or anything like that; but is watching 20 & 30-somethings wreck themselves on a weekend really going to harm her? Or will it prepare her for the real World?
Should I take her to these shindigs with the express explanation that this behavior is only acceptable when you are a productive member of society and that any other circumstance probably makes you a loser?
For the past three years (since Sis has been allowed to visit on her own), I’ve kept her far, far away from my somewhat morally corrupt friends. However, now that she’s a bit older, and summer gatherings are upon us, I’m at odds.
Any ideas?