Sadly, a lot of people don't understand this. They see a joke about a group of people and look past any sort of reasoning behind the joke and immediately go up in arms. South Park is really a great example. A lot of the humor isn't necessarily making fun of a group of people, but the people who are seriously offending that group of people.
In the context that we're talking about, I'm not sure if it even matters? What I mean is, no matter how much you try and perfect your joke, to make it obvious about who you're making fun of, someone out there will take it the wrong way. Especially nowadays, there are a lot of people who are easily offended and there are some things you ABSOLUTELY CANNOT EVER joke about. I just remember the infamous Penny Arcade comic where it was so obvious they were criticizing MMOs for having quests where you'll see a bunch of people who need saving, but can only save X number, but a group of people took it to mean they were making fun of rape, blew it WAY out of proportion, and it was just crazy.
Just know... you will never win. But I don't think that means it's not a path worth taking. Just be prepared, think about how you should respond, if you even will respond. I think it's best to just not lose cool and respond in a respectful manner.