Would colored highlights look stupid on light to medium brown hair?

It depends on how you look too, in my opinion. Some people can pull off wild colored highlights no matter what color their hair is, but some it looks absolutely hideous on. Since i don't know what you look like, I think it would look best If you put some colored streaks in the under layers of your hair, but not on the top. I actually think that looks way better on anyone than highlights all over, or on the top layers.