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As if there aren't already enough ways to start petty fights on Facebook, founder Mark Zuckerberg said the company is thinking about adding a "dislike" button. It's one of the most commonly requested features, he said.

"A lot of times people share things on Facebook that are sad moments in their lives," Zuckerberg told an audience at the site's headquarters. "Often people tell us that they don't feel comfortable pressing 'like' because 'like' isn't the appropriate sentiment."

It's not clear yet what form the button would take, or if there are other options under consideration that would allow users to express a broader range of emotions. For now, haters will have to stick with the ironic "like."