My wife's hair has been so many colors, I can't tell you the number. This past summer she had a little mishap and made it mermaid green. The attempt to correct that resulted in me coming home to a completely different looking woman every two or three days.
I love that girl... 
Mrs. Dual was naturally blonde as a child, and was naturally changing to brunette when I met her in college. However, she'd been "cleaning up" her hair since high school with bleach and blonde dye, so had no idea she'd turned a completely dark auburn/brunette color. A few years into her marriage, she noticed how dark her roots were, and was shocked. And in response, to put it back to "the way it was supposed to be" went with a brighter/lighter blonde than she should have.
Her hair got bleached white, then the blonde dye made it yellow, like the color of corn, a Lego mini-figure's head and hands, or one of our smilies here on APS.
So in a panic, we went out and got some new hair color. I talked her into trying something more red than her actual natural shade, just for variety...
Except with the ultra-bright banana yellow hair, the dark auburn came out hunter safety/punk-rock orange.
So she went to a friend's house, and came back after a third box of dye a dark auburn brunette that was close enough to her actual true color, you couldn't tell when the roots grew out.
