Slangs such as GMFU are used by teens to be more dramatic in conveying emotion, and to identify with people who keep up with the internet culture of the modern world. It assists them in conveying response within a short time, expressing personality, or following the trending discussions. Slang expressions can be more emphatic than a formal language when responding to unexpected or aggravating events. Nevertheless, due to its profanity, GMFU is rather used by teens in the informal conversations instead of in school or family. It is an emotion-filled phrase that is used as a reaction phrase in most social media sites. Know more about what does gmfu mean