what was said... but I think it's done by pulling both sides of your hair back loosely and fastening with an elastic. Lift up the side pieces that are fastened together, and brush your hair straight down to smooth the back. Then, fold/wrap the back up and over the side pieces that are joined together, rolling it into place until all ends are secure. Fasten with hairpins and a shot of hairspray.
How to Make a 4 Stranded Braid Weave via duitang.. So I went to great lengths to message the source of this photo via tumblr and she said it was a french braid that came loose in gym... Hopefully the "instructions" to this will give the same effect!