The "🆎" or "AB Button (Blood Type)" emote is a symbol representing the AB blood type, which is one of the four major blood types in humans. People with AB blood have both A and B antigens on their red blood cells and do not produce antibodies against either A or B blood types. This makes them universal recipients for blood transfusions but they can only donate to other AB individuals. The emote is commonly used to indicate someone's blood type or as a playful reference to the AB personality type in astrology.