Temporary color that doesn't damage the hair.

I'm pretty sure the dyes you get at the Hot Topic aren't damaging, but they also don't show up well unless your hair is light or bleached. Spray-on stuff will make your hair stiff, and so will like gels and stuff. If your hair is fairly light, I would go with the Hot Topic kinds of dyes. If your hair is dark, probably getting a wig would be easier.