怪我年轻是人是狗分不清
[guài wŏ nián qīng shì rén shì gŏu fēn bù qīng]
It's a bit sarcastic or self-mocking phrase suggesting regret in not being able to distinguish between good and bad people during youth because of youthful naivete. The user perhaps expresses remorse for making mistakes from poor judgments made at younger age.