<human>: TIFU by trying to help a young co-ed with a wardrobe malfunction.

College started today in my neck of the woods.  I am returning after... oh so many years.

As I left my last class today I saw a young female with some really flimsy shorts walking through a public area.  The problem was that her back-pack had pulled her shorts up on one side.  The net effect of this being a full frame of her right buttock, out for all to see.

My fuck up was walking up next to her and saying "You should maybe be careful about those shorts."  I am a middle age man with long hair.  She is a young female in a college environment.  Her response was a fairly politely delivered "Don't comment about my body."

I am bummed out that the interaction went that way.  I think that she was scared by what I said and may have been right to tell me to fuck off.  I still feel like I should have warned her that she was exposing herself to the quad... but don't know how I could have done it any better.  (At least, if I was walking through a crowd like that with my butt cheek awkwardly highlighted by my cute and fashionable shorts, I would have wanted someone to tell me.)

Can you summarize the given text in a few sentences?
<bot>: I told a girl that her butt was showing in public.  She made me feel like a sex offender.  Feels bad man.