待你长发及腰都变贞子了
[dài nĭ zhăng fā jí yāo dōu biàn zhēn zi le]
'By the Time You Have Long Hair Reaching Your Waist, You’ll Turn into Sadako.' It's a playful exaggeration referring to Sadako from the movie Ringu (Ringu being quite a famous horror movie). This indicates that waiting too long might have negative consequences.