Can smiggle liquid chalk be used in hair?

Yes, of course! I do it all the time, however, it is very wet to start off with and goes on all your clothes! You might want to make sure you wear a towel around your neck. Once you've finished chalking, you will want to blow dry it and maybe put some light hair spray in it! This will help it stay until you next wash it depending on your hair colour. Light - may take a wash to come out. Dark - may wear out eventually.