There's the chemical straight.... like a reverse perm. And there's the ceramic iron (flat iron) straight, that only lasts until you wash your hair again. OR if you're in a topical climate like I am... it lasts until you go outside for while.
I have naturally curly hair, live in south florida, the frizz central of hair! I had it straightened temporarily when the youth group high school girls got a hold of me (I was a youth volunteer minister). lol. What fun we had! But my husband HATED it when I got home. lol