Someone who can't help being everyone's friend, and has to be...everyone's friend. They do this to network, make connections, always have a place to stay, and never be disliked.
Check out the movie 'The World's Fastest Indian' with Anthony Hopkins. From befriending 10 year old boys, to transvestites, to randy grandmas, this guy can't help himself! Makes zero enemies, just several dozen loyal (and generous) friends.
Also think Bill Clinton on his path to be President. Now that we all know we were duped into thinking he was this loveable nice guy, his new name is 'slick-willie', or friendslut.