Between K.Stew's fiery orange locks and Nicole Richie's lavender dye job, it seems like celebs have officially come down with hair color fever. Always one for experimentation (witness her video for "Dark Horse") last night Katy Perry treated her Instagram followers to a eye-popping surprise—partially lime locks accompanied by a note: "SLIME GREEN FOR SPRING." Opting for more of a dip-dyed style than all-over color, Perry complemented the shock of green by hanging onto her raven-black bangs. The look reminds us of some of our favorite hair rebels, namely Thora Burch's Enid from the 2001 movie Ghost World and green-haired goddess Arabelle from the blog Fashion Pirate. We'd suggest going to a salon to get this look but (in the words of Perry) if you "wanna play with magic," check out this bright hair color tutorial over at Rookie.