Some stereotypes can be funny (who doesn't love a good blonde joke), but even there, they can get old.
Racial stereotypes however, are not, for the most part, funny. They are hurtful and ignorant. There are exceptions - like the ones between friends, and used as a form of comraderie. For a while we lived in a mostly Irish neighborhood, and the fellows would call each other "Mickey", but get offended if anyone else did it.
My ex used to call himself a kike, and it bugged the shit out of me. He did it as a form of self-defense - saying it before anyone else might. I thought it helped to perpetuate the derogatory connotation, and asked him not to do it.
There are a lot of folks who use terms like that, not even knowing what they actually mean. I have a friend who used to whisper "mexican" because, until she moved to this state, she'd never met anyone who wasn't caucasian, and thought it was a slur. Good grief.