You've probably noticed that two-toned hair has been practically everywhere these days. The biggest fans of the trend seem to be pop stars, and three of them had us seeing rainbows this week. Demi Lovato showed off baby-pink tips during a performance on Good Morning America, and Colette Carr was rocking electric-blue strands with wisps of purple. And Pink, who as of recently had traded in her signature pink hair for a more demure white-blond color, went back to her so-called roots with a teased updo. All three of these colors will give you something to sing about, but who wore her neon locks best?