I was thinking of two specific instances (luckily this sort of crap is rare and it's only happened to me those two times).
In the first instance, the person in question was my direct boss and was responsible for reviewing my code. He'd routinely call me an idiot, a retard, etc., and during meetings he'd often say things like "no, we can't give that to Jacob - he'll just fuck it up." Now, in his defense I was a pretty shitty developer at the time, but I do believe there are more constructive ways of reviewing code than calling the author a retard. I dealt with it for a few months, and finally asked his boss to transfer one of us. When I explained the reasons, this person was fired.
In the second case, my coworker was showing up to work drunk, yelling and cursing at coworkers, and routinely threatened violence -- "I'm gonna beat your ass if you don't shut the fuck up" was, I believe, a common line. Once he threw a chair through a window halfway through a (technical) meeting. Again I was too much of a coward to call him on his behavior directly, but yes I spoke to first my boss, then his, then the owner of the company. Nothing changed, so ultimately I quit.
In retrospect I certainly didn't behave perfectly: I should have confronted the behavior directly, and I should have made clear what my expectations were with regard to a professional working environment. But I was young, and all in all I'm proud of myself for not tolerating abuse (even if I didn't go about it quite right).