For this tutorial, I took Sophie as my model. Thank you, Sophie!
1. Brush hair well.
2. Divide into two equal(ish) parts.
3. Now comes the fun/tricky part. Cross the left section over the right section (or vice versa, like I did).
4. And start twisting. I twist the hair from the left to the right.
5. Keep crossing each section over and twisting each section as you do so.
6. It should start to look like a rope. See the twistiness?
7. Don't give up! You're nearly there!
8. When you think it is as long as you want it, fix it in place with a hair tie. When I first did it, I thought it would all un-twist itself when I tied it with the hair tie. But it didn't!
Oh, and by the way. You're done. :)
Optional (a.k.a Extra for Experts)
For a very glamorous-looking bun, twist the rope braid up and pin it. In my humble opinion, this looks way more awesome than a normal bun.
Oh - and Sophie, you're an awesome model!
Let me know what you think in the comments. :)