Since my hair appointment isn't for three weeks, and I've got roots showing, (It distresses me a lot, you guys, my hair is like a strawberry blonde naturally, and I swear to god it just gets lighter the darker I try to go with it. Possibly I'm secretly turning gray already. I DON'T KNOW.) I bought some cheapo DIY hair color, right? Except it says Do Not Use on hair that is dyed dark (mine).

Now, I'm fairly used to ignoring warnings on hair dye (allergy test, what?), so... what would happen if I used it anyway?