Who REALLY knows Katy Perry?  Well, apparently a super-fan.  The pop star appeared on Jimmy Kimmel Live! Monday night to take part in a game called 'Who Knows Katy?' versus one of her biggest admirers.  Katy was a little slow on the buzzer, but her calm, cool, and collected competitor had no trouble answering questions about Katy's life, maybe even a little better than the star herself.