One time my mom dyed her hair blonde, and she left it in too long and it turned green. -_-; How long did you leave iot in for? It depends on the brand, but I usually leave mine in for half an hour to 40 minutes.

A good way to get rid of extra dye is to rub mayonnaise in your hair and after while wash it out. The smell is probably at the same level as ketchup though lol.