Silly question, but have you tried talking to her? She's a human just like you. Try catching her after class. It's hard and risky, but compliment her to break the ice, and make it more than just about her hair. Ask her out, try and get her number. Treat her well.

Real life is different than porn videos for the most part. "initiating sexy hair stuff" is something you have to work toward most of the time by getting to know her, earning her trust and winning her over. There's no secret phrase that makes it instantly happen.