“I hate giving classes,” Zizek said, citing office hours and grading papers as his two biggest peeves. “I did teach a class here [at the University of Cincinnati] and all of the grading was pure bluff,” he continues. “I even told students at the New School for example… if you don’t give me any of your shitty papers, you get an A. If you give me a paper I may read it and not like it and you can get a lower grade.” He received no papers that semester.
But it’s office hours that are the main reason he does not want to teach.
“I can’t imagine a worse experience than some idiot comes there and starts to ask you questions, which is still tolerable. The problem is that here in the United States students tend to be so open that sooner or later, if you’re kind to them, they even start to ask you personal questions [about] private problems… What should I tell them?”
“I don’t care,” he continued. “Kill yourself. It’s not my problem.”
I also like Rebecca Schuman's take on this at Slate.