Watch Lady Gaga and Tony Bennett’s Christmas Duet [Video]

Who would have thought that Lady Gaga and Tony Bennett would become musical BFFs? Ever since they sang together on Gaga's Thanksgiving special back in 2011, they'd occasionally pop back up with each other. And you know what? They sound really good together! They took the stage once again at last night's Rockefeller Center Christmas Tree lighting celebration to sing "Winter Wonderland". Check it out: