Cool down.  It doesn't happen often, but it does happen – it's a big world out there, and there are some bad people in it.  Some of them find a Ham Radio now and then, and discover the delight of offending an audience.  The key word is audience. Deliberate interference and bad language are designed to make you react.  The person doing it wants to hear you get mad.  They love it.  And if they don't get it, they go away, usually quickly.  So when you hear the rare nasty stuff on the repeater,  just ignore it.  Don't mention it at all on the air. Don't mention that you're not mentioning it. 

Sometimes a repeater control operator will decide that the best way to handle the situation is to turn off the repeater or one of its functions for a while, but the rest of us should bite our tongues and be silent.