I finished grading a round of papers only to discover a documentable plagiarism case. I hate having to deal with that kind of thing. I hate having to give the stern "You're looking at an F on the assignment, a very unpleasant meeting with the dean of students, and academic probation" lecture. Even more than that, I hate it when these cases disrupt my usual working assumption that we're all adults and I don't have to yell at anyone for intellectual dishonesty.
I told them at the beginning of term that plagiarism is easier to detect than they might think, and that if they can find a paper on the web, so can I. Apparently, not everyone was listening.