When we discovered secret rainbow hair color [1] last year, we were positively entranced — and excited by the potential. If you work in a more conservative office, hiding unicorn-worthy hues in the lower layers of your mane is a great way to get in on the colorful fun without risking your job.

As it turns out, this secret strand-tinting technique is called underlights. Stylists pin up the top layers of hair, then bleach and color [2] the pieces underneath. The result is as cool as it is covert: just style your mane in an updo to show off the edgy hues, or put your hair down for a day at the office. Read on to see some examples.