a word used by people to either refer to someone as either a friend, or as a "mentally handicapped" person. or as a more popular way to say it. a retard. People use it jokingly to poke fun at others or call a good buddy (in good humor of course)
another version of champ is the white way of saying it. such as those baseball or soccer or football dads. "way to go champ! hit that ball out of the park" or short for "champion" though these ways often are not used.