OMFG, what happened to the “Gossip Girl” buzz?

The CW series about the upper East Side’s most privileged is well into its third season, and despite guest stars like Tyra Banks and Hilary Duff and “controversial” story lines like Chuck Bass’ guy-on-guy kiss, the show that was once on the tip of everyone’s tongue now seems to be in the back of their minds.

And as any teenager knows, no buzz is bad news.

“The silence is deafening,” Syracuse University Prof. Robert Thompson, a popculture expert, told The News. “‘Gossip Girl’ was like Twitter – when people first discovered it, they couldn’t stop talking about it. But the enchantment has worn off.”

CW officials say nothing is wrong. They cite the show’s steady ratings and the fact that it remains their No. 1 series in the coveted demo of females ages 18 to 34.

“‘Gossip Girl’ remains an incredibly valuable franchise for both the network and our parent companies,” said a spokesman for the network. The show, he added, “has made an indelible impact on popular culture and remains one of the most powerful brands on television, and a signature show for the CW.”

But Thompson says the network should be worried, because “buzz is like a Dow Jones Industrial Average, an indicator of things to come.”

It’s not unusual for interest in a series to level off as newer shows crop up. Let’s be honest, the “Rachel” wasn’t a popular haircut for “Friends’” entire run.

But where there was once an “OMFG” on the side of every bus, there’s now a “Vampire Diaries” ad. And because “Gossip Girl” catapulted into pop culture entirely on the back of its buzzworthiness – who is Gossip Girl? What was that song? Who makes those shoes S was rocking? – when magazines and blogs would rather pay attention to the Kardashians and Gosselins, the series is left with nothing going for it but its plot, and that might not be such a good thing.

“It’s getting a little long in the tooth,” Thompson said. “The premise of the show was so interesting and exciting in the beginning, but this season’s story lines don’t seem to be clicking. It’s not like if you watch an episode this season, you can say that it’s fundamentally worse than it was last season – it just doesn’t seem to have the shelf life of other programming.”

AOL Television’s Maggie Furlong said that even if the series’ actors land in the tabloids or on a magazine cover – Chace Crawford was recently on the cover of People, and the CW folks said there are four upcoming covers – they aren’t as much of a draw as they used to be.

“They’re no longer that interesting,” said Furlong, whose story about “Gossip Girl”-inspired Halloween costumes garnered only one comment from readers. “That would have never happened a year ago. Now everyone wants to argue about the Gosselins instead.”