长发及腰那是贞子
[zhăng fā jí yāo nèi shì zhēn zi]
It translates to 'if the hair reaches the waist, then it's Sadako (the protagonist from The Ring).' This plays on pop culture fear, using the image of long-haired, eerie Sadako to make a comment that long hair could be beautiful but here humorously hints at something potentially scary or creepy.