[Bigiron]

Mr Koh Ban Heng, 69, dislikes it when women continually flip their long hair on buses. He encounters this three to four times a week.
“I’ve met ladies who kept flipping their hair every few minutes. Their hair may have dandruff or whatnot, which makes it not very hygienic,” said the courier firm employee, adding that he moves away from these women.

This is very true.

May be they no wash their hair...or feel being bored so need to flip and play with their hair