Keith Richards Doesn't Know Who Christina Aguilera Is

Christina Aguilera joined the Rolling Stones for a song for their recent documentary Shine A Light. And despite being very popular, some people still don't know who she is. Like Keith Richards.

"This girl came out and I was like, 'Who is that?' I had no idea. I'm still not sure who that is. She can sing, though. And she looked good."

Hilarious!