there is no specific psychological concept or term called the "borderline personality smirk." It is possible that such a term or phenomenon has emerged or been discussed in more recent times, but I don't have access to informationdate.
It's essential to remember that personality disorders, such as Borderline Personality Disorder (BPD), are complex conditions with various symptoms and characteristics. BPD is typically characterized by a pattern of unstable relationships, self-image, emotions, and impulsive behavior. People with BPD may struggle with emotional regulation and have difficulty understanding their emotions and the emotions of others.
If the term "borderline personality smirk" has been used in a specific context or source, it is essential to consider the credibility of the information and the expertise of the author discussing it. Mental health conditions should be approached with sensitivity and respect, and it is crucial to rely on reputable sources and professional expertise when discussing or researching these topics.