The Myers-Briggs Type Indicator (MBTI) is a widely used personality assessment tool that groups individuals into 16 types (based on 4 dimensions). The popularity of MBTI and the availability of online MBTI assessments have led to the increasing usage of MBTI, including sharing and displaying their MBTI types as part of their online identity. This study investigates the trend of combining social media and personal assessment tools such as MBTI by exploring how people interpret their MBTI and how they form impressions and interact with others based on others' MBTI labels. Through a thematic analysis of posts from the subreddit r/mbti and a two-part online survey, people use MBTI for self-reflection, validation, and personal development, while often overestimating their type. The 4-letter MBTI also helps in understanding interpersonal relationships, but can reinforce stereotypes in first impressions. Based on these findings, we show how ''one MBTI (type) does not fit all'' and explore how modified MBTI stickers (with percentage information) can help reduce bias on social media profiles.