The moms of America are speaking to Johnson & Johnson, and they’re not just disappointed—they’re very, very mad.

What they’re up in arms about is an online commercial that J&J’s Motrin pain reliever brand released onto the Web targeting mothers and the pains they may get from carrying their babies and young children around. It’s not the attention from a pharma company that these mommy bloggers a objecting to; it’s the implication that some mothers are carrying their kids around as fashion accessories rather than as valuable bits of posterity.

And they’ve gotten J&J to pull the ad off the Web.

The ad, actually posted online at the Motrin.com Web site, offers a female narrator with a tongue-in-cheek take on “baby wearing.” “In theory, it’s a great idea,” she says. “Supposedly it’s a real bonding experience…But what about me? Do moms that wear their babies cry more than those who don’t? I sure do!”

“I’ll put up with the pain because it’s a good kind of pain; it’s for my kid. Plus, it totally makes me look like an official mom. And so if I look tired and crazy, people will understand why.”

Well, the Twittersphere exploded with complaints from moms, and presumably at least some dads, who believe J&J’s McNeil Consumer Healthcare Unit, the division actually in charge of the ad, was deriding their parenting and implying that they were “crazy”. Within an hour of the first tweet about the ad it was the No. 2 topic of discussion on the microblog service. From there it moved to bloggers and inevitably to response videos posted on YouTube. There were calls to J&J and calls for boycotts. (“I have thrown away all Motrin in this house… will not be buying any more EVER,” blogs Single Mom Meltdown .)

Finally on Monday, a post appeared on the J&J official blog site. Signed by Kathy Widmer, vice president of marketing for McNeil Consumer Healthcare, it explained that the ad had been a misfire on the company’s part.

“[The ad] was meant to engender sympathy and appreciation for all that parents do for their kids, but did so through an attempt at humor that missed the mark and many moms found offensive,” she wrote, adding that McNeil was taking the ad off the Motrin Web site (but warning that a version of it could still be found in some newsstand magazines.)

“One bright spot is that we have learned through this process—in particular, the importance of paying close attention to the conversations that are taking place online,” Widmer concluded. “It has also brought home the importance of taking a broader look at what we say and how it may be interpreted.”

Commendable lessons to learn, and I’m sure they’ll be inscribed on the doorway to the conference rooms at both J&J and at TAXI New York, the agency of record for the Motrin brand. (My apologies if they did not handle this online campaign.) I’m sure future campaigns will be focus-grouped and measured within an inch of their lives.

And there’s no denying that if it elicited this kind of reaction, the ad was a bad one—as in, disastrously ineffective. Unfortunately for McNeil, it’s destined to live on on YouTube as a constant reminder of the perils of assuming too much about your audience.

Even when that assumption is just that they can laugh at themselves a little.

Interestingly, while most posters took offense at the implication that they were “crazy” for wearing their babies, a small number—admittedly a minority but more than a handful—resented the supposed implication that because they didn’t tote their kids in slings, they didn’t care as much about their offspring as people who did.

“So because I didn’t wear my girls, I’m not an ‘official’ mom?” asks the ironically named Jaime@JustAddLaughter. “Seriously, what a horrible campaign!”

“Seriously” seems to be a key word in this whole flap.