bun

Reader's Digest 11月号の記事 'Life in these United States' からの引用です。
Lice was detected on a student at my grandson Ryan's school, and the teacher told the girls in Ryan's first grade class to wear their hair in a bun to discourage the lice. Needing clarification, Ryan asked, "A hot dog bun or a hamburger bun?"

・Oxford English Dictionary: A hairstyle in which the hair is drawn back into a tight coil at the back of the head.