When my boyfriend left for work the other night, I had dark brown hair, and was quietly sitting in front of the computer reading this thread.
And when he came home a few hours later, he found me in the bathroom, almost white-blonde and missing three inches of hair, studying the directions on a jar of Passion Red Manic Panic (Hooray spontaneity!).
I know everyone says Manic Panic sucks, and that Special FX is the way to go, but I wanted pink hair and I wanted it right then, dammit! I'll order SFX later.

Pink, it was love at first sight...
(Sorry for the crappy quality; I was going to fix the colors in Photoshop, then realized that would defeat the point of showing the actual color of my hair.)
Also: Thanks, everyone, for the inspiration. ^^