I never did myself, but, I unknowingly assisted on of my friends.
It was during gym class and she had asked me if she could borrow my sweater, and unlike me she was skin and bones pretty much, so I didn't see the harm in it. She had gone into the locker room five minutes before everyone else had, she said she wasn't feeling well.
So the rest of us girls get in the locker room, we didn't see her or anything, so we figured she must have gone to the nurse's office. We all get ready to, and most of the girls went on to chapel, me and three of my other friends decide to wait for her to get back, (her non-gym clothes were still there.) And then I notice that there's someone laying down in the handicap bathroom, so I peek under, it was our friend. I say her name and she doesn't respond, and my other friends ask what's going on, so I slid under the door and unlocked so we could all get in.
When we looked closer, she had a shirt tied around her neck and to the other end of the shirt was the sweater I had loaned her, she came to and told us what she had done...
after that, she had gone into counseling, she was there 'til mid June, a couple weeks later, we had a little party, we burned the sweater and the shirt in a bonfire, that day was very emotional, but liberating too...