Christina Aguilera and Jimmy Fallon surprise crowd with NYC subway performance

Christina Aguilera and Jimmy Fallon may have fooled passersby into thinking they were little-known talents when they performed Aretha Franklin's "Think" in a New York City subway station. They were in disguise.

Video of their performance, posted Thursday on YouTube, shows Aguilera sporting dark glasses and a floppy hat. Fallon is seen wearing a wig, goatee and mustache before they reveal their identities to the crowd.

"We'd like to do one more song for you if you don't mind right here. First I'd like to introduce ourselves. My name is -- my name is Jimmy Fallon," he says to a cheering crowd. "And this is Christina Aguilera!"

The two then perform "Fighter," one of Aguilera's hits, released in the early 2000s. 

USA Today reports it was filmed for Thursday's "Tonight Show."