This is an acronym for the phrase, Gay Boy For Real.
An exceptionally annoying person, usually know as GBFR only because he is in the same room as you. Do not give a GBFR any personal info, as they will see this as an attempt to have a life long friendship. WARNING! Do not give GBFR your address or phone number; he WILL attempt to contact you, and speak endlessly about his hoser life.