As a lowbrow, take-on-all-comers venue for satire, MAD Magazine has trafficked in shock on a regular basis. Only on one occasion did MAD cross the line to the point that the publisher himself, the great William Gaines, decided to issue an apology to the magazine’s subscribers. The April 1974 issue dispensed with the usual iconic face of Alfred E. Neuman (who wasn’t on every cover in any case) in favor of a realistic painting of the unmistakable hand gesture denoting, in aviary fashion, “Wyncha go fuck yourself?” The headline read, “The Number One Ecch Magazine.” (“Disgusting” in MAD parlance, see also “blecch” and “yecch”.)

In any case, confronted with the option of placing an upraised middle finger on their shelves, many newsstands refused. Gaines decided that the newsstands and the many, many offended readers had a point and sent out “hundreds and hundreds” of apology letters. (Does anyone out there reading this have one of those letters?) For some readers it was a watershed moment, and they would never return to reading the magazine. MAD obviously survived, but it was a tough moment for the magazine.
 

MAD publisher William Gaines
 
Maybe they were looking to offend some people—just three issues earlier, in MAD 163, the cover declared, graffiti-style, “MAD Is a Four-Letter Word!” Gaines would later imply that the “usual gang of idiots” had come up with the idea of the cover and that he wasn’t that into it, but it seems like a quintessentially Gainesian move from the man who successfully defended First Amendment issues when he withstood the withering scrutiny of the Senate Subcommittee on Juvenile Delinquency in 1954 and insisted that the definition of “bad taste” for a horror comic might be a cover in which “a man with a bloody axe holding a woman’s head up” was holding the head “a little higher so that the neck could be seen dripping blood from it, and moving the body over a little further so that the neck of the body could be seen to be bloody.” (See here for more of his testimony, including the images he discusses in detail.)

According to TV.com, “The magazine itself was pulled and returned/destroyed from many newsstands and is now a hard-to-find collector’s item.” (True enough, it’s available for $50 on Amazon as I write this, although on eBay you can pay for less for one, it looks like. Awesomely, an uncut cover sheet for that issue sold for $40 just a couple of weeks ago.) As a user on the Collectors Society forum put it, “Many parents were P.O.‘ed and either complained or just canceled their subscriptions. William Gaines ended up sending out a letter to all subscribers in which he apologized for the breach of good taste—probably the first time Gaines has ever done such a thing.”

In an interview in the May 1983 edition of The Comics Journal, Gaines discussed the incident:
 

Dwight Decker: Do you feel you might have been isolated in New York, putting out the comic books [meaning the “Vault of Horror”-style comics in the 1950s], that you couldn’t really judge the reactions of the people in Oshkosh?
William Gaines: Definitely. And this is still true with MAD. We put out an issue, oh, maybe 89 years ago now, which is what we called “the finger issue,” which was, “MAD is number one,” [giving the finger] and holy Moses! The guys called me into a cover conference to look at the thing, and I said, “That’s okay. It’s not too funny, but it’s all right.” And we put it out and the roof fell in. And I was sitting here sending out apology letters by the hundreds and hundreds to people all over the country—from Oshkosh. ...
Decker: A friend of mine just told me the other day—he lives in Connecticut—he hasn’t read an issue of MAD since that issue.
Gaines: That issue so offended him?
Decker: Yes.
Gaines: Incredible. To me it’s incredible but there’s no question that a lot of people felt that way.

 
Here’s Gaines on Canadian TV in 1977 discussing another occasion when MAD got some flak from a very different corner of the world: