待我长发及腰我吓死你可好
[dài wŏ zhăng fā jí yāo wŏ hè sĭ nĭ kĕ hăo]
This is humorous and somewhat dramatic play-on words, expressing an agreement of when I finally let my hair grow long enough down to waist, it would surprise the audience, meaning I would make a drastic but unexpected change.