In How I Hate Your Mother, an episode of The New Adventures of Old Christine (airdate 10/1/08), Christine's ex-husband asks her for the engagement ring he gave her. Soon Christine is looking for the ring while her brother Matthew watches.
CHRISTINE: Hey, don't you find it outrageous that Richard wants to take back the ring that he gave to me and give it to another woman, as if our whole thing never existed?
MATTHEW: You know, you don't need a ring to prove your marriage existed. Nobody is ever going to forget what happened in that house.
MATTHEW: The realtor still can't unload it.
MATTHEW: You might as well have Indians buried in the backyard.
Based on Matthew's character and tone, it's clear he's being facetious. I'm sure he doesn't have anything against Indians. Nor do the show's creators, presumably.
But consider the meta-message here. Namely, that it's normal and acceptable to equate house-buying horrors with Indian burial grounds. In today's culture this reference doesn't need an explanation; everyone gets it.
Even if the creator are making fun of this notion, they're also unwittingly perpetuating it. If that isn't their intention, it's arguably the result. Is that something they want to take responsibility for?
What to do about it
The way to handle something like this isn't to be "politically correct" and ban the joke. It's to add a further commentary on it...to really mock it...to make sure viewers know it isn't true.
For instance, the following lines might do trick. By piling a stereotype on a stereotype, it would be clear that Christine and Matthew were dealing in stereotypes. Some viewers might not realize the last line was intended to make the whole thing facetious, but I think most would.
CHRISTINE: Oh, Matthew. You shouldn't stereotype our proud Native Americans.
CHRISTINE: They might come and scalp you.
More accurate but less amusing might be this:
CHRISTINE: You mean because Indians are all spooky and scary?
MATTHEW: No, Christine. I mean because archaeologists might declare the property a sacred site, which would ruin its resale value--this is going right over your head, isn't it?
For more on the subject, see TV Shows Featuring Indians.
P.S. Old Christine is one of the few TV comedies I watch. I recommend it.