A person who is homosexual beyond the standards of society. Such person usually does things gay or "overtly" gay to earn him the title.
Someone who does something stupid earns the nickname too.
You almost hit oncoming traffic! You're overtly gay!
*Jon enters the room; everyone is whispering*
Jon: Are you guys telling secrets? My turn. I gave a man a lapdance.
Phil: Oh, man, that guy is overtly gay!