Katy Perry probably dyes her hair more often than she changes her socks. Maybe not. We hope not. But she is changing colors again. This time her new hair will be slime green. "I'm really excited about slime green, but I hope my hair doesn't fall out," she told E! News. We can't wait to add another Nickelodeon Gak (check out the commercial below if you forget that reference.) color to our Katy Perry hair photo gallery.