人家说你真不纯
[rén jiā shuō nĭ zhēn bù chún]
This translates to someone saying, 'You really aren't innocent/pure,' implying this user knows well how the real world works. It could be used humorously for self-identification, admitting some life wisdom or worldly sophistication, or sometimes it could suggest a bit rebellious nature to challenge so-called pure ideals.