It was the "excuse me" that echoed around Democratic politics.
In their intense Flint, Mich., debate, Bernie Sanders pointedly said to Hillary Clinton in the heat of one exchange, "Excuse me, I'm talking."
Sanders has an $18 trillion unicorns-dancing-on-rainbows spending program and a paranoiac's view of Wall Street, but nothing is quite as disqualifying for the feminist left as his alleged "condescension" in this moment and a couple of others (in two other instances, he asked if he could finish, please).
As far as decorum goes, the Clinton-Sanders spat was like a dispute over what dinner fork to use at a four-course meal at the Four Seasons compared with the food fights during the Republican forums.
It takes a primatologist to try to unravel the dynamics at a GOP debate, whereas the Democratic debates are being scored by the kind of people who worry about microaggressions and need ready access to safe spaces.
The debate flap demonstrates, once again, how feminism is caught between its dual insistence that women are indistinguishable from men and at the same time are due special consideration because they are uniquely vulnerable to slights, intended or unintended.
No one should have to worry about Hillary Clinton on this score.
She isn't a college sophomore making her first nervous presentation before a public-speaking class. She has been in public life since 1978, and on the national stage since 1991.
She was a highly engaged first lady, a senator from New York, the secretary of state and, twice, a presidential candidate. She debated Barack Obama 26 times in 2008.
She has weathered more public controversies than any politician in America — with the exception only of Donald Trump — and endured countless congressional hearings. Yet her allies think she can't bear a couple of sharp words from Bernie Sanders?
It's not just that they think it's out of bounds to interrupt her; they think she can't handle someone trying to stop her from interrupting — and while she's distorting his record.
During the exchange in question, Hillary was misleadingly accusing Sanders of opposing the auto bailout. She used Jesuitical wording to make it sound as though his vote against the TARP Wall Street bailout meant he didn't want to extend federal aid to Detroit.
It was when Sanders replied to this attack that Clinton tried to break in, and Sanders issued forth with his "excuse me."
Bernie Sanders isn't exactly a threatening figure. The 74-year-old socialist can fairly be accused of an excess of charming irascibility, but he's about as malicious as a Peter, Paul and Mary song.
His problem is that he doesn't do identity politics well, or at least not exquisitely enough to meet the standards of the contemporary left. So he's stepped into a couple of (ridiculous) charges of sexism, and he's constantly being accused of insufficient racial awareness.
At the Flint debate, Sanders said whites don't know what it's like to live in the ghetto, which he surely thought was innocuous enough, but opened him up to charges of tone-deafness — he had used the dated word "ghetto" and supposedly implied that only blacks are poor.
Tsk-tsk. It's not easy being an old-fashioned, class-obsessed left-winger in today's Democratic Party.
A general election won't have the same hothouse left-wing atmosphere of the Democratic primary, but Hillary's potential Republican rivals should nonetheless take note.
Taking on Hillary will require some finesse because most people feel, simply as a matter of good manners, that women should be afforded more courtesy. We may have jettisoned almost every standard of personal conduct, but this ember of gentlemanly expectation still lives on.
Bludgeoning Hillary into submission, the Trump method of debate, won't work. Ted Cruz, whose lawyerly arguments easily slip into genuine condescension, would have to calibrate accordingly. If a socialist grandfather can be made out to be Archie Bunker, imagine what awaits a Republican.
Rich Lowry is editor of the National Review and author of the best-seller "Lincoln Unbound: How an Ambitious Young Railsplitter Saved the American Dream — and How We Can Do It Again. He has written for The New York Times, The Wall Street Journal, and a variety of other publications. Read more reports from Rich Lowry — Click Here Now.