Do you dye your hair? A lot of geeky girls seem to enjoy dying their hair. I LOVE dying my hair strange colors. 
my favorite was Manic Panic atomic turquoise.
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it was also pink for awhile.
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I've also dyed it black before.
But to get the pastel or bright colors I had to bleach the heck out of my hair which damaged it bad.
So now I just have some blonde highlights. So when I color my hair only a few strands show the color. I don't like it as much but only get highlights touched up every 3 or 4 months instead of bleaching my whole head every 5 weeks lol.
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Last month it was Pink.
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Right now it's Purple.
Next month I'll probably go back to the turquoise.