By Johnny Lieu
World-famous musicians busking on the subway is totally a Jimmy Fallon thing now.
Joining the likes of Maroon 5 and Miley Cyrus in a (not so) random act of singing was pop queen Christina Aguilera, who hid under a floppy hat and sunglasses to sing a cover of Aretha Franklin’s “Think” at the 50th Street station in New York City.
Of course, what would a star be without the hits: Aguilera also performed an acoustic version of “Fighter” to a very enthusiastic crowd, and lots of cowbell from Fallon. …