Just one, and it sucks because it was my closest friend in my program. I found out that she'd plagiarized much of a paper she'd written for a class we took together--though the prof didn't fail her; just gave her a C because it was a pretty crappy paper...don't think the prof wanted to get involved in dealing with any disciplinary drama since she was just visiting for the year...and then I later found out that her boyfriend was basically co-writing all of her papers for her. Of course she broke up with him once her coursework was done...shady.
I didn't say anything to the powers that be, but it irks me that she's still in the program. Maybe I should have reported her...
