Clearly the clever young men behind the social networking juggernaut Facebook didn't know about moms. Especially lactating moms. Anger them at your peril.

According to an Australian paper, Facebook has recently removed photos of nursing mothers from members' homepages and banned all photos of breast feeding where the breast is even slightly showing.

As any mother could have told them, that was like pouring gasoline on a fire. Now, thousands of Facebook users are on a rampage. A Facebook group called "Hey Facebook, Breastfeeding is not Obscene" (a real mouthful, that) already has nearly 20,000 members, with more joining every day.

According to the article, spokeswoman Meredith Chin said Facebook, with some 31 million users worldwide, did not prevent mothers from uploading photos of themselves breastfeeding their babies, but it did remove content that was reported as violating Facebook's terms of use.

"Photos containing an exposed breast do violate our Terms and are removed," she said.

No word yet on how much baby there has to be covering said breast. But if the bikini-clad girls in some of the ads on the network are any guide, not very much.

As the furor grows, Facebook might want to take a page from Mattel Inc's (NYSE: MAT) playbook: Never underestimate the wrath of moms.