How can i get my usually straight hair, to look naturally curly for school tomorrow?

I am 14 and I have naturally straight blonde hair, with a kink in it, so every day, for school, i blow-dry and straighten after my shower the kink out. But i want to have it curly tomorrow. So far i've had a bath, and let my hair dry naturally, while i keep scrunching it up now and then. Its noe dry and wavy but how do i get it to stay like this for school tomorrow? I know if i just sleep on it, ill wake up tomorrow and it will be really knotty and fizzy, so then i'll have to brush it and then it will go all poofy! And i really don't want to loose my waves during the night -or the day! How can i keep it wavy through-out the day!? HELP PLEASE!