1 packet Ghoul-Aid Kool-Aid is equal to:
2/3 packet Lemon Lime + 2/3 packet Ice Blue Raspberry Lemonade + 2/3 packet Grape Kool-Aid, and
4 drops Black + 4 drops Green McCormick

They are all gray that is very slightly brown, though Ghoul-Aid is more brown in sunlight and more gray in indoor light. 2-3 packets Ghoul-Aid per 10 g yarn makes black.

2 parts Red + 1 part Yellow + 5 parts Blue McCormick, Safeway, and Kroger liquid food colorings makes a nice steel gray.