A teacher in Chesapeake, Virginia, has been fined and sentenced to 6 months in jail for punching a student. More information on the student behaviours that sent the teacher over the edge can be found here.
I would bet that there are very few teachers out there who have never ever wanted to hit a kid. I know I've had my fantasies of doing so. There are just times and situations where a kid pushes all your buttons and almost dares you to get physical. It is exceptionally rare that any teacher would act on such impulses. And while I could never physically harm a kid (unless s/he was endangering someone else...including me), I admit that I did smile when I read the article about the Chesapeake teacher.
Perhaps it is because thoughts of revenge activate the pleasure centers in the brain. I am always fascinated about our more "primitive" impulses. My students are, too. Recently, my seniors talked about how weird it is that this 3-pound wad of fat sitting in their skulls can do so much. Hopefully, they'll use it wisely.