Katy Perry Surprises Fans In London

There was a special screening of Katy Perry‘s Katy Perry: Part Of Me in London this past Thursday.  Much to the surprise of the hundreds of fangirls, Katy showed up!  The superstar sat with her fans and enjoyed the film.  Katy Perry: Part Of Me will be in American theaters on July 5th.  Did I mention this is in 3D?  If there are bikini scenes count me in!

Check out the reaction of her screaming fangirls below!