萌比你脑子缺根弦逗比你脑子少根筋
[méng bĭ nĭ năo zi quē gēn xián dòu bĭ nĭ năo zi shăo gēn jīn]
'Cute and lacking in sense; foolish and absent-minded than you' - This implies a somewhat childish and silly side of the user's personality. Also humorously means that they think someone is more foolish or less clever than them.