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Meredith goes ra-ra ra-ah-ah!

On Friday's Today Show, Meredith Vieira morphed into the biggest pop star on the planet right now: Lady Gaga!

For the morning show's popular Halloween episode, Vieira dressed up in the singer's infamous 2010 Grammys get-up. (The "Poker Face" singer was roundly mocked for her silk orb-like Giorgio Armani Prive dress at January's bash.)

Vieira wasn't the only staffer channeling pop sensations, either. Natalie Morales dressed as teen phenom Justin Bieber -- complete with that famous haircut!

Ann Curry, meanwhile, sported the aviatrix look as the late Amelia Earhart. Al Roker opted for a classic costume: Superman.

Also on hand for the costume party: Will Ferrell and Tina Fey, who channeled their characters from the upcoming animated flick Mega Mind.

Tell Us: What'd you think of this year's costumes on The Today Show?