It's not a joke anymore

At what point does a joke stop being a joke?  At what point does it become just being hateful or mean?

I've always tried to approach humor in this way.  A joke isn't something you tell to hurt someone you care about.  You should never use humor to tear someone down in order to make someone else laugh.

I should say now that I could probably use a thicker skin, but I am very curious.  When does a joke stop being a joke?  When does it stop being just fun teasing and turn hurtful?  How is it okay for people to say really mean things and then go, "I was only joking?".  Does that suddenly make what they said less offensive?

I'm probably going to end up on the hypocritical end of this, but it's one of those things I'm trying to work on.  I'm trying to stick to my guns and my morals when it comes to how I treat the people around me.  I'm trying to not just go with this mentality that we need to beat down people that don't meet our "standards" or act the way we think they should.

How about jokes on sensitive issues?  When does it stop being a joke to tell someone to get a job, lose that weight, or any other subject the person you're talking to is already sensitive about?

Okay, now I'm rambling so I'll just end this with my questions?


Where do you draw the line between a joke and outright meanness?  How do you deal with jokes based on race/sex/sexual orientation?  How do you deal with a person that is clearly just being hateful and hiding behind humor in an attempt to mask it?