Howard Flight and Lord Young have joined a long list of people who have realised that there are some things you can't say. So when and why is an utterance likely to get you in trouble?
We have come to learn as either public or private individuals that there are certain situations that mean careful self-censorship is required.
For all the talk of freedom of speech in liberal democracies, poorly chosen comments can end careers, lead to arrest, or just cause offence and embarrassment. So what are the unwritten rules and regulations of speech?
Howard Flight got into trouble for talking about "breeding".
"We're going to have a system where the middle classes are discouraged from breeding because it's jolly expensive, but for those on benefit there is every incentive. Well that's not very sensible," he said in a newspaper interview.
You probably wouldn't have to stop too many people in the street before you found somebody who agreed with that sentiment, but critics have said Mr Flight's remarks smack of "eugenics".
And eugenics is a bad thing in the popular mind, at least in part due to its association with the Nazis. But there's more to the story than that.
If you had given a speech about eugenics in the latter part of the 19th Century, it would have been a fairly unremarkable position to take. Eugenics' pioneer, Francis Galton, was a respected scientist and his theories continued to have currency well into the 20th Century.
The University of London - as its own history notes - had a department with "eugenics" in the title until 1963.
Galton was one of the first people to suggest the heritability of human traits and he openly advocated encouraging talented people to have more children. But once the Nazis took eugenics to a horrible conclusion by exterminating "undesirables", the subject and the word itself was soon highly negative.
Mr Flight's critics compared his remarks to a speech given by Keith Joseph in Edgbaston in 1974. The speech dealt with Mr Joseph's analysis of the problem of large numbers of children being born to young mothers who were incapable of properly raising them.
But to some his language - "our human stock is threatened" and "social classes 4 and 5" - was a nod to eugenics and therefore enough to stop any aspirations to be Conservative party leader.
In Mr Flight's case it's not easy to even argue he was advocating eugenics. A eugenics supporter might advocate encouraging "superior" people to have more children and "inferior" people fewer.
What Mr Flight actually said was it was wrong to effectively encourage one set of people over another. The critics were instead seizing on an implication. But the lesson is that a term - or even an implication of that term - can become unsayable within a couple of generations.
Conclusion: Eugenics has gone from a serious scientific discipline to a basic pejorative term. Avoid.
WHO YOU ARE
If you are the kind of public person whose pronouncements are parsed to an almost pedantic degree, you must exercise extra caution.
The current Pope found that out in 2006 when, during a lecture tackling the relationship between faith and reason, he quoted a reasonably obscure historical dialogue between the Byzantine Emperor Manuel II and a Persian.
In that dialogue, the emperor said: "Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached."
Nobody reading the whole speech by the Pope could have thought he was endorsing this quote. But the reporting of the speech generated a wave of protests in Muslim countries, and was even linked to the death of a nun in Somalia.
If he had been an ordinary person, or even a politician without an international profile, his words would have been unlikely to have spread so far so fast, and those encountering it would have been more likely to have read the context before passing judgement.
Conclusion: Very often what you can't say is about who you are.
WHERE YOU ARE - DON'T SAY 'BOMB'
Of course, that's not to say ordinary people can't get themselves into a whole lot of trouble by saying something wrong.
Paul Chambers found out via a criminal conviction and a £1,000 fine that it's unwise to even jest about threats to airports.
His case represents the zenith of stringent post-9/11 air security law enforcement. In January, Mr Chambers wrote on Twitter: "Crap! Robin Hood airport is closed. You've got a week and a bit to get your [expletive] together otherwise I'm blowing the airport sky high."
He was subsequently convicted of having sent a "menacing" message and fined. Critics have claimed it is a miscarriage of justice and he has become a bit of a cause celebre, with Twitter notables like Stephen Fry backing him and numerous people tweeting the same message with the hashtag "iamspartacus".
But he's not the first person to suffer as a result of an air security related joke.
The cases of a British student arrested in the US for joking about a bomb and an Iraqi sea captain who said he had two bombs in his briefcase show how the authorities are rarely amused.
The ordinary person knows that terrorists are not usually inclined to winkingly announce the presence of a bomb in their luggage as a daring double-bluff to airline staff.
But the airport security operative is obliged to be stony-faced and literal-minded, because while the chances are negligible that the joker actually is a terrorist, the stakes are rather high.
Conclusion: You can't say bomb in an airport. Not even if you immediately say you were joking. Probably best not to even say it about an airport.
Being a role model, who's expected to be an inspiration to ordinary people, rather constrains what you can say.
Footballer Glenn Hoddle found this out the hard way. His ruminations on karma in a Times interview in 1999 were enough to get him the sack as England manager.
"You and I have been physically given two hands and two legs and a half-decent brain. Some people have not been born like that for a reason."
The point was made at the time that the England manager is inevitably going to have contact with disabled footballers.
And there were some who wondered whether he might not have been a bit more fireproof if he hadn't just had three poor qualifying games - a defeat against Sweden, a home draw against Bulgaria and a laboured win against minnows Luxembourg.
Tiger Woods also got in trouble - although not nearly the same level of trouble - when in an offhand moment he suggested that he had played like a "spaz" during a difficult tournament.
Conclusion: Watch what you say if you are a sporting role model, and be particularly sensitive in your comments about disabled people.
Labour MP Tony Banks got into hot water when he called William Hague a "foetus" in 1997 and suggested Conservative politicians might want to rethink their views on abortion.
And the Labour deputy leader Harriet Harman had to apologise last month for calling Lib Dem Danny Alexander a "ginger rodent".
Both remarks took place at party conferences, where it is understandable that comments will be widely publicised.
Former Conservative MP Ann Winterton got herself sacked as a shadow minister after making a joke about Pakistanis, at a rugby club dinner in 2001. She was then effectively suspended from the Conservative party in 2004 after making a joke about the 23 Chinese cockle pickers drowned in Morecambe Bay at a dinner.
In both cases, comments filtered out and were widely publicised because they were made by an MP - and an MP with a track record at that.
But comedians also suffer after going too far. Billy Connolly was lambasted after joking about the kidnapping in Iraq of the Briton Ken Bigley by Islamist militants. "Don't you just wish they would just get on with it?" he said.
Even in a small comedy club gig that line would have had an audience wincing, but at a theatre venue it was inevitable the "gag" would leak out and draw negative coverage.
And comedians have failed to get away with a host of off-colour jokes. Jimmy Carr got into trouble for joking about gypsies on BBC radio. Alan Carr had to apologise for a quip about child kidnapper Karen Matthews.
Conclusion: Even ordinary people might do well to avoid potentially offensive jokes.
You would also do well to watch which country you're in.
Some might find it ironic that the Islamic Solidarity Games should be cancelled because of a battle over the correct appellation for a body of water. And yet that is exactly what happened in January.
Iran insists on calling it the Persian Gulf, but there are some countries on the opposite side of the water that prefer Arabian Gulf. Trouble soon flared over logos and medals.
The Iranian authorities have made clear that any airline flying into the country must use Persian Gulf on its in-flight monitors. Any visitor would be wise to bear this in mind.
A similarly bit of nominal geographical controversy can be found in the Balkans. Use the term Macedonia in Greece, particularly in north-western Greece, to refer to the Former Yugoslav Republic of Macedonia and you may be the recipient of more than a raised eyebrow. They might even call it "Skopia", something that would no doubt irk Macedonians.
Conclusion: Keep up to speed with territorial issues that might make you want to curb your speech.
PRIVATE MADE PUBLIC
Many of the most career-mauling comments ever made have been decidedly private ones that somehow squirmed out into the public arena.
When Labour government spin doctor Jo Moore notoriously described 9/11 as a "good day to bury bad news" she would have been horrified at the thought the comment would be made public.
So too Gordon Brown must have felt his heart sink when he realised his description of a voter he had encountered as a "bigot" had been broadcast on television via an unnoticed radio microphone.
John Major's famous off-camera "bastards" remark fits neatly in the same category.
They all offer a stark lesson on watching what you say.