Get a wavy hair styler?

My friend's friend, Cindi, has amazing hair. She can wear it curly, straight, or wavy. My favorite is the wavy. I asked her how she did it, and she said that she put some sort of gel in her hair, then attached something to the top of her hair dryer, and it made her hair wavy. I was wondering if this is true, and where I could get it?? I've always loved my hair to be wavy but it's an extremely rare occasion that it is. Please help!