Shiek is affected by touching the masked Link somehow.

All of a sudden, the small amount of Sheik's hair that was visible from his cowl started to turn a bright orange-red, and his skin tone darkened from pale to sandy brown. He looked at his hands in confusion, then snarled, "What have you done to me?" Before Link could say that he had no idea what was going on, Sheik threw a Deku Nut onto the ground, and disappeared in the flash of bright light it created. Now that he was gone, Link stared at his hand, realizing what had happened. The spell must be contagious, and touching the wearer will actually turn someone into a Gerudo. Link had always been at least a little mischievous, and immediately he thought about the fun he could have with this. Surely, after all, it could all be cured with more magic later. Unbeknownst to Link, his own short, yellow hair had turned the exact shade of red of a Gerudo's, a side-effect of extending the spell.