怎么提到他你就不笑了

This sentence translates as 'Why did you stop smiling when mentioning him?' By adopting this pseudonym, one potentially exposes their sadness, depression, or disappointment resulting from talking about someone special. It could indicate that they have some complex emotions towards that specific person. Maybe they are upset or disappointed because things don't go as expected, or they miss someone but don't want others to know that he is so important to them. The phrase is often used as an ironic way in context when the person becomes more reserved, quiet or even depressed after the mention, showing a contrast to their usual outgoing demeanor.