CLICK HERE TO CHECK OUT KATY AND JOHN'S MATCHING COSTUMES!

Katy Perry threw a huge birthday/Halloween party for herself this weekend at the Magic Castle in Hollywood.  Katy turns 28 this Thursday and her birthday bash was definitely the place to be this weekend.  Kristen Stewart was there, Neil Patrick Harris, DJ Skrillex and of course Katy’s guy John Mayer.  Katy dressed as a sultry vampire and John dressed as a vampire slayer!  Supposedly
Katy has fallen for John and she thinks she can change his ways by playing hard to get. She recently told John she was open to see
other people. Once Katy turned her back on him, he started chasing her again!"