Supposedly, since growing more sensitive to racism, since feminist critiques of sexism and sexist humor, and with our new concern about not offending, humor was cleaned up. Racist and sexist jokes supposedly went the way of public hangings. Big surprise: not so.
In fact, my impression is that more sexist and racist jokes are told now than say a decade ago. How does this work? Simple: it seems okay for members of targeted groups to tell racist and sexist jokes on themselves. In fact, from what I see on late-night cable TV comedy shows, to say nothing of subscription stations and channels, the bulk of jokes told are racist and sexist. But it's all okay so long as the people telling the jokes are members of the targeted group.
It's decidedly not okay. The point is, the jokes are being told.
I know it's all supposed to pass as self-deprecating humor, and audiences are supposed to be aware of that. It's also supposed to be a kind of power-play, an adoption or usurpation of the inherent prejudice, much the same as gays adopted the previously offensive word, "queer," and feminists have done the same with other terms.
But it doesn't work with humor. The reason is that, as I say, the jokes still get told and so the put-downs are achieved. The fact that the jokes are told by members of the targeted groups, in the spirit of poking fun at themselves, may work with some members of an audience, but there'll be a lot of others who ignore or forget who told the joke and just savor the dirty dig. In this way, stereotypes are continued and supported and eventually work against the targeted group and the joke-tellers themselves.
Racist and sexist jokes shouldn't be funny to anybody; most of them are nasty little expressions of prejudice, and that remains true regardless of who made them up or told them.
The trouble is, you can restrict who tells a joke, but you can't restrict who finds it funny. And if the joke-tellers and the audience are all members of the targeted group, what's the point? It's one thing to poke fun at yourself, but quite another to have some comedian doing it for half-an-hour or an hour with joke after joke after joke. Racist and sexist jokes are put-downs, period, and they're ethically wrong regardless of who tells them.