The gesture represented by "🖕" is commonly known as the middle finger. It is a hand gesture where the index finger is extended upwards while the other fingers are clenched into a fist. This gesture is considered offensive and vulgar in many cultures, expressing strong disdain, disrespect, or defiance towards someone or something. The "Middle finger effect" refers to the impact or reaction caused by this gesture, often resulting in offense, confrontation, or negative social consequences.