A banner featuring the famous Grumpy Cat meme flies over Comcast Tower in Philadelphia, where net neutrality supporters celebrated Thursday's FCC vote on open-Internet rules. Courtesy of Fight for the Future

Grumpy Cat is giving a big middle claw to Comcast. In celebration of the Federal Communications Commission’s newly approved open-Internet rules, net neutrality supporters on Friday flew a 2,000-square-foot banner featuring the Internet’s favorite feline over Comcast Corporation’s 58-story headquarters in Philadelphia.

The massive banner featured a photo of the ubiquitous Internet meme Grumpy Cat along with the phrase, "Comcast: Don’t Mess With the Internet." The phrase was followed by the hashtag #SorryNotSorry.

The splashy stunt was sponsored by Fight for the Future, Demand Progress and Free Press, three organizations that have been aggressively campaigning for rules that prohibit broadband providers from throttling content or offering Internet “fast lanes.” Those rules passed a key hurdle on Thursday when the FCC voted to approve a proposal by Chairman Tom Wheeler that supporters say will protect net neutrality, the principle that all Internet data should be treated equally by broadband providers. The proposal is still subject to a review process and may face court challenges from ISPs such as Comcast that say Wheeler’s plan will stifle innovation and bog them down in utility-like regulation.

Grumpy Cat apparently disagrees and is willing to soar over the tallest building in Philadelphia to prove it.

In a statement Friday, Evan Greer, campaign director for Fight for the Future, said Internet users have shown that they won’t tolerate Comcast’s “blatant attacks” on free speech. “Let this be a warning to every goliath company, government and institution of power in the world,” Greer said. “If you mess with the Internet, the Internet will mess with you. And the Internet always wins.”

The “Grumpy Cat” meme was made famous after a photo of a grumpy-looking cat named Tardar Sauce went viral on Reddit. The low-key feline is not usually one to gloat, but she apparently will make an exception if, um, she believes in the claws.

See the groups’ full Tumblr post here.

Christopher Zara is a senior writer who covers media and culture. News tips? Email me here. Follow me on Twitter @christopherzara.