Reader T.B. writes:
The fact that it's become a snowclone almost makes it an empty claim. You can be sure that something else will soon pop up to replace X as the last acceptable form of prejudice…
Beyond obesity, speech patterns, and red hair, a few searches of media sources and books turn up examples citing prejudice against Romani as being the last acceptable form of racism:
 He believes that abuse targeted at travellers has become the last acceptable form of racism, which is why he plans to dispel Gypsy and traveller myths in the force with a new one-day training course on traveller awareness.
 Discrimination against Gypsies and Travellers is said to be the last "acceptable form of racism".
And similarly against Asians:
 Racism against Asians, in particular, is one of the last "acceptable" forms of racism in America.
Against Islam, Arabs, or Middle Easterners in general:
 It is the last bastion of Orientalism, the last acceptable form of racism.
 Said calls anti-Muslimism the acceptable face of racism, arguing that 'Malicious generalizations about Islam have become the last acceptable form of denigration of foreign culture."
 Smearing all things Arab remains the last acceptable form of ethnic bigotry in America.
 The museum will help to negate the malicious generalizations about Islam and unexamined presuppositions that have become the last acceptable form of denigration by the media.
 She told the 2009 Conservative Party conference that anti-Muslim hatred had become Britain's last socially acceptable form of bigotry, and claimed in a magazine article last October that taking a pop at the Muslim community in the media sold papers and didn't really matter.
Also against various forms of Christianity:
 Make no mistake, my brothers and sisters, at this time, in this world; Catholicism is now acknowledged as the last acceptable form of discrimination.
 In August 1993 the fight to end the “last acceptable form of bigotry” against evangelical Christians found its most powerful and unexpected ally.
 And that is that the last acceptable form of bigotry left in America is bigotry directed at orthodox people of faith, and particularly Christians.
 Christian bashing - and portraying Christians as simple, ignorant, narrow-minded , hypocritical and even violent - has become the last acceptable form of bigotry.
 Is it allowed only because bigotry against Catholics is the last acceptable form of discrimination?
 We must boldly stand against any who attempt to degrade our Christian heritage. We must identify them as practicing one of the last acceptable forms of bigotry and hatred: Christophobia.
[2012[ Anti-Christian prejudice is the last socially acceptable form of bigotry in this country. People are scolded by society for saying anything anti-Semitic, racist or even homophobic. But you can say anything you want against Christians, and people will smile or laugh.
And even religion in general:
 Religious leaders have been arguing for years that intolerance toward religious believers is the last acceptable form of bigotry in this country.
Among the commonest instantiations of the template are references to homophobia:
 We'd reached a moment when homophobia finally ceased to be the last acceptable form of bigotry.
 Anti-gay bigotry may be the last "acceptable" form of discrimination remaining in American politics.
 This is homophobia, the last acceptable form of bigotry.
 "Legally you (gay people) have the same rights in the UK but in America it's the last acceptable form of prejudice."
Then there's prejudice against conservatives:
 In polite society, conservative-bashing is the last acceptable form of bigotry.
 Sean, it is the last acceptable form of misogyny in this country. Hatred, prejudice towards conservative females.
 Potshots at Republicans are the last socially acceptable form of discrimination. Would you blog that Jews are smarter than Muslims? Or that whites are smarter than Hispanics? This is no less offensive or hurtful. It is always so interesting to me that the people who preach the loudest about tolerance are usually the ones being the most vocal about their intolerance for others.
 Reitz represents him critically, betraying an anti- Americanism that is perhaps the last acceptable form of xenophobia among European intellectuals: Reitz remarks that 'American aesthetics' is the 'real terror.
 Anti-americanism is the last acceptable form of racism in modern Britain.
Against Yankees (in the limited sense of Americans from north of the Mason-Dixon line):
 Let me start by saying that, among Texans, hating Yankees is the last acceptable form of bigotry.
 Our goal is to stamp out the last acceptable form of bigotry in Texas: hating Yankees. Except I can't get nobody to join.
And against Welsh people:
 Without wishing to whinge (although I feel I've been in Wales long enough to compete in this national sport), it seems anti-Welsh sentiment is one of the last acceptable forms of prejudice in modern England.
Against short people:
 Mr English has our sympathy as a victim of the last acceptable form of teasing. In his song, Short People, Randy Newman indulges in abuse that would not be allowed with any other group.
Against old people:
 … age discrimination remains the last acceptable form of discrimination …
 Age discrimination - the last acceptable form of prejudice - must be made illegal immediately," Ms Jopling concluded.
Against people on welfare:
 The stigma against people on welfare seems to be one of the last acceptable forms of prejudice.
Against working-class people:
 At its most disconcerting, this has evolved into a culturally sanctioned "class bigotry" in America, in which pejorative stereotypes of the white working class are freely disseminated in popular culture and uniformly embraced across identity politics lines as the last acceptable form of prejudice.
Against rich people:
 John Walsh - a wealthy, self-made corporate chieftain - believes he is a victim of the last acceptable form of discrimination.
 Julian Fellowes, a man who looks like he was born in a quilted smoking jacket and begged his parents to read him Burke's Peerage at bedtime, calls "poshism" the "last acceptable form of discrimination". He doesn't mean in a good way.
Against mentally ill people:
 It's not surprising mental ill health is seen as the last acceptable form of discrimination when our law forbids people who've had a breakdown from serving as a juror, company director, school governor or MP.
Against people with genetic disabilities:
 As stated by Elizabeth (cited in Chapman 2002), a woman with a genetic disability, 'I mean it is really the last acceptable form of eugenics, isn't it?'
And even against people who eat inexpensive food, or get up late:
 I am a victim of what is perhaps the last acceptable form of prejudice: late-riser bashing.
 I have long suspected that many who argue against cheap food might be sneering at those who eat it, indulging in one of the last acceptable forms of class prejudice in New Britain.
As usual with superficially-nonsensical turns of phrase, this one apparently means something different from what it says. It says that X is the last acceptable form of Y, where X is a negative evaluation of some group, and Y is negatively-evaluated term for negative evaluations. It means that people who think of themselves as free of Y nevertheless hold attitude X, or at least accept the fact that others hold X. It can't literally mean that X is the last negative group evaluation of this kind, or even that it's one of the last few, since that's so obviously false. Instead, "the last acceptable form of Y" here just means something like "a form of Y that most people don't recognize as being Y at all".