微笑掩饰内心的悲伤
[wēi xiào yăn shì nèi xīn de bēi shāng]
Literally translates to 'smiling to mask/cover one's inner sorrows'. The netizen chooses this ID possibly because of wanting to present a cheerful appearance despite having internal pain or distress. Such a username reflects on concealing true emotions through facial expressions that contradict their feelings.