上课觉觉下课闹闹
[shàng kè jué jué xià kè nào nào]
It humorously describes the actions of sleeping ('juejue') during classes (when they should pay attention) and then making noise and being boisterous ('naonao') once the lessons finish. A relatable depiction especially among young Chinese students who like using cutesy repetitive language. The username could indicate rebellion against strict classroom discipline but also imply irresponsibility in studying.