HotDamnImAPhiMu,
That's hillarious! Good for you for telling her that. The fact that she later taught your lesson to another new member shows that she has grown into a worthy Phi Mu Lady.
Speaking of which- MANY times at parties I have seen girls who are members of other sororities (who shall remain nameless) wearing their letters (lavaliers, shirts, etc) while smoking and/or drinking and/or being obnoxious. It's bad enough to make a fool of yourself without letters on (b/c some people "see" your letters when they see you), but to actually be wearing letters while participating in "unladylike" behavior is just... ugh!
All of my sisters here make it a priority to not be wearing ANYTHING with ZTA on it when going to fraternity parties, whether they plan on drinking or not. Obviously some of the other sororities here don't care about their growing bad reputations.
I once was even polite enough to mention to a small group of members of another sorority that they still had their lavaliers on, so they wouldn't get in trouble. Whaddya know? They just rolled their eyes at me!

Well they certainly don't deserve their letters or anyone else's.
Oh yeah, and at least in my chapter, if we see a sister acting out-of-line, we descretely tell her, "Your crown is on crooked". I think that's a cute, yet effective phrase since the 5pt crown is one of our symbols.