想念先生
[xiăng niàn xiān shēng]
'想念先生' is composed of '想念 (xiang nian),' which means 'missing,' and '先生 (xiansheng),' meaning Mr. /sir. This implies someone misses someone else respectfully. It might indicate that the nickname user misses his respected teachers in the past or some wise and respectable gentlemen he/she admires.