笑脸醉人哭脸慎人
[xiào liăn zuì rén kū liăn shèn rén]
A smile can charm people (醉人 means intoxicating, suggesting something that captivates people). On the other hand, crying expressions should be used cautiously because it could cause discomfort (this comes from a popular Chinese phrase indicating something is disturbing). It may describe an internet user's dual persona when facing different situations.