Gossip Girl actress Leighton Meester is also an aspiring singer, as we know.

To that end, the good girl gone bad joined Weezer on stage during their Halloween concert at Hammerstein Ballroom in New York City on Halloween Night Saturday.

Leighton helped Rivers Cuomo sing Weezer’s new single “(If You’re Wondering if I Want You To) I Want You To.” Nat Wolff of the Naked Brothers Band also joined!

Check out the clip of Leighton and Weezer rocking out live below ...

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Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.