Acronym for Johnny Just Come: Nigerian slang used to reference someone who is naive or new to a situation/place.
Omo, you be jjc, you just land yankee!
That guy is a jjc, he's been here for only two dayz
Nigerian slang used to describe a foreigner - usually a Westerner - recently arrived in country and who is often unfamiliar with local customs and therefore a target for 419 or scammers
See dis JJC, he bring plenty Dollar-o