Kool-aid does work but only if your hair is light.
You just mix the kool-aid packets in with some conditioner then put it on your hair with like an unused toothbrush and wrap it in foil then wait 15 minutes and wash it out.
You could also do this with RAW hair color they sale at hot topic, that's what I used and I LOVE it and it washes out over time.
that's the color I used. & it's only like $13.