Tina Fey, Jack McBrayer and Alec Baldwin Tina Fey, Jack McBrayer and Alec Baldwin

Liz Lemon, you don't look a day over fabulous! After five years and countless awards, the Emmy-winning 30 Rock marks its 100th episode with an hourlong outing about, of all things, a 100th episode. "We figured that TGS, the fake show, started at the same time our show did, so their 100th episode would coincide with ours," explains executive producer Robert Carlock.

But that's where the similarities end. While 30 Rock has been renewed, tonight's milestone finds TGS facing the ax now that new Oscar winner Tracy is in hiding to avoid the pressure of being taken seriously. "He's smart enough to know he's an idiot," says Carlock with a laugh. "The plan is to get him back on the show and back to where he was five years ago, running down the street with a plastic lightsaber."

Along the way, there are cameos by Regis and Kelly, Matt Lauer and Rachael Ray; a hysterical pregnancy for Jenna; the return of one of Liz's exes; and a guest spot by Michael Keaton as a janitor who really has his work cut out for him. "Amid all of this chaos, we also come to realize that there is a slow gas leak in the building," says Carlock. "And it is producing the kind of hallucinations and flashbacks one might want in a 100th episode." Sounds like a gas!

30 Rock airs Thursdays at 10/9c on NBC.

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