"Hippie punching" is in the news around the world these days — Paul Krugman, "Macroeconomic Hippie-Punching", NYT 5/26/2013; "Gordon Campbell on the govt's latest bout of hippie punching", Scoop Media NZ 5/27/2013; "« Hippie punching » et puis tant pis !", L'est-éclair 5/28/2013;
One definition is offered by Michael Berube, "Libya and the Left", The Point, Spring 2012:
Those who believe that there should be no enemies to one's Left are fond of accusing me of "hippie punching," as if, like Presidents Obama and Clinton, I am attacking straw men to my Left in order to lay claim to the reasonable, vital center.
But hippie-punching seems sometimes to include the rhetorical abuse of leftists by people who self-identify unashamedly as rightists.
Krugman's introduction to the term is documented in a blog post from 7/19/2010, "Loona Bimbertons Of The World, Unite!":
Henry Farrell explains it all. One of his commenters says that the US term for what Henry calls Bimberton-kicking is "hippie-punching", which is about right; although when it comes to politics the proper term is DFH.
What’s particularly noteworthy is that Bimberton-kicking becomes more, not less prevalent when, as has happened consistently this past decade, the DFHs are proved to have been right. It’s understandable, of course. How can the self-proclaimed sensible centrists continue to regard themselves as sensible, when they were wrong about Bush, WMDs, financial deregulation, and so on? Only by becoming even more disdainful of the unwashed ruffians who got it right.
In the linked blog post, Henry Farrell evokes the motivations of a fictional character:
Saki’s short story, Mrs Packletide’s Tiger, has a wonderful opening paragraph which finishes:
She had also already designed in her mind the tiger-claw broach that she was going to give Loona Bimberton on her next birthday. In a world that is supposed to be chiefly swayed by hunger and by love Mrs. Packletide was an exception; her movements and motives were largely governed by dislike of Loona Bimberton.
If the American left could be substituted for Loona Bimberton, this would stand as an astute psychological analysis of Clive Crook’s latest effusion on how Obama could get his mojo back.
The cited comment is by Doctor Science was:
Is there a reason did you not say “hippie-punching”, which is considered the term of art for this rhetorical trope? Or is “hippie-punching” an exclusively American expression?
The term seems to have been introduced into mainstream journalism in September of 2010, when Susan Madrak used it to confront David Axelrod over the Obama administration's treatment of the political left. Greg Sargent, "Liberal blogger directly confronts David Axelrod, accuses White House of 'hippie punching'", Washington Post 9/23/2010:
Top Obama adviser David Axelrod got an earful of the liberal blogosphere's anger at the White House moments ago, when a blogger on a conference call directly called out Axelrod over White House criticism of the left, accusing the administration of "hippie punching."
"We're the girl you'll take under the bleachers but you won't be seen with in the light of day," the blogger, Susan Madrak of Crooks and Liars, pointedly told Axelrod on the call, which was organzied for liberal bloggers and progressive media.
I just got off a White House conference call in which I asked David Axelrod if he ever heard of the term “hippie punching”.
“Are you there?”
“Yeah, I heard you. Go on.”
Basically, after Axelrod told us how wonderful we were and how much they needed us to close the enthusiasm gap in this election, I called him on it. Like, yo Dave, here we are, liberal activists who give money and GOTV, and the White House needs to punch us in public so no one thinks they take us seriously?
And then he said, like, your feelings don’t really amount to a hill of beans in this crazy mixed-up world when we’re TRYING TO SAVE THE COUNTRY, and then I said excuse ME, we’re not talking about my feelings here, how am I supposed to motivate my readers when you treat them like the town ho?
As these discussions suggest, the term was already current in certain circles. Nine months earlier, for example, Doug Johnson, "Why don't you all f-fade away?", Balloon Juice 1/23/2010:
I do get sick of the way everything revolves around boomer narratives. We all joke about hippie-punching, but when Joe Klein goes off on the "far left" (or whatever he calls us now), that is what he thinks he's doing.
The earliest use of the term that I've found comes from the right — Frank J. Fleming, "Are Our Kids Punching Hippies?", IMAO ("Unfair. Unbalanced. Unmedicated.") 2/12/2008:
One day when I was but a young boy, I was walking down the street with my dad to the hardware store. He suddenly stopped, crossed the street and punched a man. When he returned, I ask, "Father, why did you punch that man?"
He turned to me and said, "That's a stupid question." Then he punched me.
It was a stupid question, because who my dad punched was a hippie. Back then, everyone knew that you punched hippies, but I've noticed that this knowledge may not be being passed on to the next generation. If there's one thing I've realized over the past few years is that hippies are not being punched quite enough [...]
We have a war right now. Our military is overseas killing terrorists — the violent form of the hippie — so they can't be here punching hippies for us. We have to do that ourselves. To keep this a country safe for soldiers to kill evil foreigners without hearing whiny protests, we have to make it unsafe for hippies.
Fleming followed this up a few days later with a "Hippie Punching FAQ" IMAO 2/19/2008:
Unfortunately, American society has gotten lax on hippie punching to the point I thought I should write an FAQ to better explain the issue to those who don't currently engage in the punching of hippies. Hopefully one day this will all become so natural again that a hippie punching FAQ will be about as necessary as a flipping people off in traffic FAQ.
Though Fleming's FAQ is satirical, the hippie-punching part is literal:
Q. Where is best to punch a hippie?
A. About the face. That's where the hippie is most annoying.
Q. What is a hippie?
A. Generally, a hippie is an annoying, useless. Actually, less than useless, as they are not happy until they prevent other people from being useful as well. In fact, Scientists have determined that the only evolutionary purpose of a hippie is for punching as a stress release for productive members of society.
Q. Are there any other uses for hippies than punching them?
A. No, there are no other uses.
Q. Couldn't they be ground up and used as chum?
A. They're too gummy.
We've already got several psychodramas going on here – the metaphorical girl you'll take under the bleachers but you won't be seen with in the light of day, the serious people maintaining their self-esteem through public abuse of the metaphorically unwashed ruffians who got it right, the metaphorical woman whose movements and motives are largely governed by dislike of the metaphorical Loona Bimberton. Back in 2008, Fleming evoked a perhaps-deeper psychodynamic layer:
Q. Just to be clear, are you talking about physically striking hippies or are you talking metaphorically about "punching" hippies through rhetorical means or through your actions against narcissistic hippie ideals?
A. Can't it be both?
Q. Well, one of those is a valid point and the other I'm pretty sure is assault.
A. Maybe you're a hippie.
Q. Since you're writing both sides of this FAQ, you're actually accusing yourself of being hippie.
A. Shut up. I really hate you.
Q. Now this is getting a little weird.
A. You're the reason dad never loved me!
A. Why won't you die!
Q. Okay… let's dial this down a little. It's not me you're angry at. It's them. They're the ones at fault. Remember?
A. Are you going to have me hurt people again?
If we take hippie-punching to mean the rhetorical abuse of leftists, whatever the motivation, then Fleming's posts count as the origin.
The earliest usage of the phrase from the left that I've found so far is Doug Johnson, "Contempt for the audience", Balloon Juice 9/9/2009:
I still haven’t recovered from the one-two punch of the David Brooks hippie-punching manifesto on the dignity of the tea baggers and Time magazine’s Glenn Beck-fluffing cover piece.
What bothers me most about both pieces is the contempt that the authors have for their audience. Everyone knows that print media is dying and that it will end not with a bang but with a 3000 word whine about how much we’re going to miss it. I wonder this, though: has an industry ever thrived while having as much contempt for its customers as national print media does? [...]
And with Brooks…where do you even start? His stock-in-trade is shitting on “progressive elites”, but who does he think reads his books and columns? Who does he think watches him and E. J. jerk each other off on the Snooze Hour? Who does he think, in effect, pays his salary?
Note that David Brooks is depicted as punching hippies from the self-identified center-right, to help maintain his role as the NYT's house rightist, whereas Modrak's question for Axelrod depicted the Obama administration as punching hippies from the center-left, in order to establish its centrist cred.
But if you want more about how different people interpret this term, see the comments on Doug Johnson's 10/3/2011 Balloon Juice post, "Meet you all the way".