Things look like they are getting pretty serious between Katy Perry and John Mayer. The two celebrated Halloween and Katy's birthday early when they stepped out together in costume and headed to a party in Hollywood.
Katy was dressed as a vampire bride, while Mayer was a zombie hunter. Both of them pulled out all the stops for their characters. Katy wore fangs, a velvet cape and red contact lenses, while and Mayer showed up with a prosthetic nose and chin.