人不猥琐狂骚年人不奇葩狂少年
[rén bù wĕi suŏ kuáng sāo nián rén bù qí pā kuáng shăo nián]
If people aren't frivolous when young, then they won't become crazy unique youth. It shows someone who regrets not being bold or unconventional enough in their teenage years, reflecting on the past and valuing freedom and eccentricity in youth culture.