The tasing incident I found most disturbing was the tasing of student Mostafa Tabatabainejad at the UCLA library a while back. It was before, "don't tase me, bro." Watching this made me feel less safe in the world, and the feeling has stuck with me to some extent.
He was tased at least 4 times while other students begged the officer to stop.
I don't think people should be tased unless they are committing or threatening a violent act.