I just had three girls walk past me in succession with their hair all piled up on top of their heads in increasing ridiculous manners, and it took all my effort not to both laugh and grimace in distaste.
Buns are flattering anywhere from the crown of your head down, so about halfway between where your hair on your forehead starts, and finishes on the nape if your neck.
Even a cute little bun behind your ear works! But when it looks like your hair coordinated guinea pig nested and fell asleep on top of your head? No dice.