Witches are Bitches (1996)

Sinopsis

When the sinister advances of two beautiful witches are spurned by a shy young girl, they cast a wicked spell. Tarana (Anna Malle) changes ravenna (Victoria Lee) into a guitar whose music bewitches all the sweet and innocent girls who hear it ... turning them into nasty sluts. But the guitar soon falls into the hands of London, a scruffy rocker. He doesn't know it's evil power ... but why should he care as beautiful girls are suddenly stripping off their clothes whenever he plays it.