幼稚园小朋友学前班大儿童
[yòu zhì yuán xiăo péng yŏu xué qián bān dà ér tóng]
It roughly translates to 'Big child from kindergarten', this kind of online name expresses immaturity and innocence of childhood, sometimes with an intention to create a playful and endearing image of oneself as still possessing childlike qualities in adulthood.