Buy a doughnut-shaped bun form (like Conair Bun Maker, $3, shown here) and a braided hair extension that matches your hair color (try POP Clip-In Braid, $9, ulta.com).
Brush hair into a super-tight high ponytail that sits slightly behind the top of your head. (If your hair is curly, wet it and then brush it back). Fix any flyaway strands with hair spray.
Attach the bun form by pulling your ponytail through the doughnut hole, then pinning it to the base of the ponytail.
Divide the ponytail into two even sections and fan them out over the doughnut, securing with a ponytail holder. Wind any extra hair around the base, pinning it in place.
Wrap the braided extension around your bun, hide the ends underneath, and then pin.