奇葩臀妹96怪味萌男69
[qí pā tún mèi 96 guài wèi méng nán 69]
This is likely referring humorously or affectionately to individuals with distinct personalities: peculiar but interesting female(s) from 1996 and males from 1969 marked with quirky charm. The combination of oddball (qipa/puzzle-pieces) buttocks girl 96 and flavor-mysterious cute guy 69 uses playful exaggeration of personality traits, probably indicating the users consider themselves unique characters or fans of those sorts of personas. However, such a username also demonstrates its whimsy with numeric year references. It would seem particularly nonsensical to outsiders.