Acronym for a German-language song called "Mein Besseres Ich" ("My Better Me") by the artist Protagonist. Commonly used as a hashtag in social web (e.g. on twitter) for posts and comments referring to all kinds of human behavior of acting particualarly individualistic or "more special" than others. The song the hashtag is referring to satirically addresses the very same behavior in its lyrics.
"I hate people extensively posting pictures of themselves on Instagram #MBI"
"Immer diese arroganten Selbstdarsteller #MBI"
"Hipsterism is over #MBI"
