JUST found out about something called hair chalking. Basically, you get your hair wet, rub chalk down it, then run it through your flat iron/curling iron, and you have some instant temporary color! I'm not sure how easily it washes out yet, since I've only found this cool tutorial on how to do it so far, but I think I'm going to do a little bit more research to see if there are any risks on putting chalk in your hair. It looks like you need to make sure it doesn't have any oil or wax in it, but other than that, it sounds just fine.
I just read some other thing that it may dry out your hair if you do it often, but I personally would save it for special occasions or going out. Which, going out is a special occasion anyways!
I wish I had found out about hair chalking before Radcon, but, there's always next year! Plus, the Renaissance Faire, and summer bonfires... and summer in general!
Anyways, just wanted to pass this along so anybody else who hasn't heard of hair chalking knows about it now! I'm definitely trying it soon! I have an old hair straightener that I don't use much to use for it too!