Can you get waves by using a bar of soap?

yes.

I have used this method, usually like a night before last resort to the fact i haven't brushed my hair in weeks or months. slightly moisten hair rub a dry bar or soap as you would brush your hair. then brush (of course never brush your hair dry, if dry add water) apply durag until morning. upon waking wash hair (preferred in shower) using just water and a brush keeping wave pattern. after shower apply oil and brush (apply a wave cap or durag if needed). I usually apply this method heading to meetings or interviews, remove durag just before & brush. Save